Looking for a tried and true carb 365 hp 454 magnum top end build, something someone has done, built, dynoed and run in their boat with good results. I would like to just mess with the top end and cam. I was thinking of putting in a roller cam and all roller valve train in, I would like to have the square port heads that are on it possibly ported and polished with new valves and springs, and intake in carb. My goal in 450-500hp.

A friend of mine has 454's that are close to what you are looking for. They were originally Merc. 420's but the long block is the same as the 365's. They are stock bottom ends .060 over. The original iron 990 heads were ported with 2.25 intake and 1.88 ext. valves. Compression is 9.25 and the cams are comp. 11-451-8 230/236 @.050 and .547 lift. The intakes are weiand 8018 dual planes with holley 850's on top. The motors were dynoed and at 32* timing one made 475hp and the other made 495hp. Not sure why but one motor was set at 32* and the other at 30* timing to sync them at 475hp

This isn't the greatest 454 build or one I would copy necessarily but it is a good example with dyno results.

If your considering going any further than simply reconditioning your stock heads with a good valve job and maybe adding 2.25 intake valves IMHO your better off going with a new set of aluminum castings. The intake runners on a GM Iron rectangle port head are too big for a 454 to begin with and increasing the port volume by porting them will only compound the problem. Yes you will gain high lift flow but the gains will only be worth while with a cam in excess of .650 lift

The last set of GM iron heads I had ported and flowed cost about $1000 and after all the work they still didn't flow what a set of Brodix heads of the same Intake volume flow right out of the box which are about $1350 a set for bare castings.

IMHO the Brodix BB-1 castings with 280cc intake runners would be a great starting point for 454 turning less than 5500rpm

Last winter I rebuilt my mag heads, compcams ultra pro roller rockers, flat tappet cam, emi thunder with long risers and weiand 177's in my cig bullet. Dynoed at 572hp/611 ftlbs. Picked up 10mph so far but need to go from B1 26's to 28's which should get me upper 70's.

This is about as tried and true as it gets. Although Tyler's kits were originally designed for the EFI/MPI series of engines
the same recipe will apply to your older Mag carb engine with the appropriate changes of course.

Well worth the call I believe.

http://www.crockettmarineengines.com/products.html

I worked with wayne272 over the phone on his builds, he seems happy with them. I believe his stated power was with only 4.5 psi of boost.

I should add that your stock 454 mag heads reconditioned with quality hardware are more than capable of meeting your goal of 450-500hp without the added expense of extensive port work. The cam and valvetrain will be the key to good results, and don't forget aftermarket exhaust will be a must.

Does anyone have cam and valvetrain sugestions? I would like to have all roller valvetrain. I have looked at some of the xtreme energy comp cams, not sure on what people think of those. What brand of valves and springs are best? I will be putting on a set of gil aluminum manifolds and stainless risers, will these flow enough?

Thanks for the help guys!

Gils will work fine with your build. They are ok to about 600hp.

A Crane 731 cam(#139011), Isky valve springs and hardware, Airgap Intake, and Holley 800cfm will get you into the hp range you're looking for.
I would mill the heads .020 also to bump the comp ratio to about 8.9.