The 088 heads will not flow better than the pro comp. However, I would not recommend the pro comp heads due to their casting quality .

How fast do you want it to go???? It will take about 475hp to touch 70mph. Unless you have hydraulic steering, you really don't want to push it beyond 70.

91 octane then?????

Built right, you should be able to pull 475 on regular....

i didn't say they were no good. i said there was better. they fell in my lap for 200 bucks. better costs 2000 bucks on up. afr and brodix can run 2000 per head. even poirted-bigger valved iron ovals cost about 350 to 500 to buy and a 1500 porting-new valves machine shop bill. so factory rectangle heads at under 1000 a pair in runnable condition are usually the best bang for the buck but not the best bang...i have seen used edelbrocks show up on craigs for 1000. used procomps occasionally for 600. but craigslist is a crapshoot. and they are gone in one day.

It looks like that thing was stored in the ice melt bag!!

Self ventilating!

It would be worth calling Bob Madara at Marine Kinetics - 585-654-8583. He can offer you some very good info on cam and head selection, and he also can supply you with your parts at a price that is very hard to beat. I bought a set of AFR 265 heads from him for a little over $2k / pair already set up with the good roller springs and inconel exhaust valves (which are an absolute necessity on a performance marine engine). He can also custom design a cam for you that will be tailor made for your application.

You need to start by establishing a budget. Like others said, you may find that the $$ involved with setting up a set of stock iron heads for a good high lift roller cam will approach the cost of a set of new aluminum performance heads. The AFR 265's are about perfect for a 454 ci engine. You may find that Bob suggests a single plane intake over a dual plane intake for a performance marine engine. Not sure if there is a significant difference here if you already own an intake, but you want to run an oval port intake with the 265's (and optimally, port match them to the "roval" intake port shape.) DO NOT skimp on valvetrain components like pushrods, lifters, rockers, and springs. A stable valvetrain is perhaps the most critical factor in longevity of your marine engine. With the aluminum heads you can probably go a point higher on the CR. Piston choice might be a limiting factor here - flat tops on a 454 will probably only provide around 9.0:1 comp, but you need to calculate all of this before you select your pistons.

I will tell you that a 454 with the AFR 265's, a decent hyd roller in the .226 / .236* @ .050 / 112* LSA with around .610 lift should easily get you to better than 550 HP with the right intake, carb and exhaust. The tube headers are going to produce the best power, but you have to be careful about cracks in the tubes due to the design of them - they are under more structural load due to the long lever arm action of the primaries / collectors. A set of Stainless Marine would be ideal, and if you find a set of Gil's or something similar for a good deal, that would also work.

Regarding silent choice, it all ties into your goals for the boat, but if going for max power it will be a limiting factor for cam selection. As an example, I am running a set of Lightning headers on my 489 with AFR's and a relatively mild .226*/.230* / 114* LSA hyd roller cam, and I had reversion issues with silent choice attached to my headers. You wouldn't think this would happen, but my theory is that the aggressive cam profiles of the roller (which get the valve off the seat quicker than a flat tappet) combined with the efficient exhaust port and longer stroke came together in a "perfect reversion storm" for my application. I think it would be possible to design a high lift roller cam at a wider LSA angle and still run a good flowing manifold or header with a silent choice type exhaust without the reversion, but you are definitely trading off 15 or 20 HP on the top end to do this (just estimating here - Bob would be the man to ask). That is why you need to put pencil to paper and define your goals and budget, and then give Bob a call. Good luck with your build!

Unless I missed it here, what is your budget? As some have mentioned the AFR 265 head is the perfect head for a 454. I have built an engine around this head in the past, and I can speak with personal experience, is a great product. I ran my engine with 10.4:1 cr and had no issues at all running 91 octane gas. Budman II post above has a lot of great info in it. As he suggests call Bob Madera, he designed the engine I mentioned above. You cannot build a high horsepower 454 engine with 8.8 cr, at least not N/A.

My current engines are/were 8.8:1 with a decent sized cam (232/237) and they are pretty much done making power at 51-5200 rpms. Look at the merc hp 500, hp 450 or the 420's all are low compression and merc says to prop all of them at 5200 rpms. Which pretty much validates my experiences with my old builds. With the right cam and compression ratio, you can easily make 475 hp with the 088s. With the AFR 265 you can take that number to 550 or so. It just depends if you have the budget to buy new heads. Now if yours need to be rebuilt, buy all means buy the AFRs. I had $1000 in machine work, new seats, and guides in a set of old 188s. Plus I needed new springs, retainers and locks. When It was all said and done, I had close to $1500 into my iron heads. For $500 more I could have had new, modern heads.

Also- as some have already mentioned- stay away from MSD stuff. Buy a thunderbolt distributor with the Merc V-6 module and you will have a much more reliable ignition system as well as more money in your pocket, and you won't give up any performance.

Ramos48 here Rebuilt his 454 mags last year. Brodix 294 rect port race rite heads, mild hyd roller , a tad under 9:1 static, made 507hp at 5600rpm. 544ft lbs at 3800rpm. Can was 227/233 duration. This engine was not dead at 5200rpm.

That engine was not a low compression turd. Not bad for a low compression 87 octane build. It was not lacking low end torque. Not bad for a 454 with race rite rectangle heads and their standard non raised exhaust ports.