iron heads; 9:1. those 3cc domes in that rotating assy are about right. is your builder balancing these engines? those 049's getting any port work? done right they are superior to rectangle stock heads. cams...marine kinetics. he also has good prices on the best quality valvetrain components.

Make sure your builder checks lifter bore clearance, and it wouldn't be a bad idea to make sure you have sufficient valve to guide clearance, especially if you plan to lean on this and run it in cold water. Also, if you are replacing the exhaust valves inconel is a must for any performance marine build.

I have Gen IV 4-bolt main 454s with 049 heads. Granted, the heads have been massively worked and the it's all top of the line guts, but I have an issue with losing a 330 Merc at 4500 rpm.
What I am about to say is not performance driven, and I may be kicked off this site, but I think you need to hear it:

Cast cranks, stock rods, even cast pistons (had to swallow hard on that one) are okie dokie in the motors you have. I'd be confident up to 400 hp or so and 5200-5400 rpm. They have been the staple of the industry for decades. I have owned, and I have friends that have owned, BBC Mercrusiers that do 500 hours without a hitch. In a naturally aspirated boat where initial torsional loads are NEVER as great as dumping the clutch and launching a 1970 Chevelle off the line, even 2 bolt blocks are fine. Unless you are going to do your "big motor" conversion to them right now, a forged crank and all the rest of it is wasted money. You're looking for "quick, fast and in a hurry" to get back on the lake, and that's what I'd do. Basics, good machine work, good assembly, check it all and put that baby on the water. Start gathering parts and take your time picking out stuff for you killer motors, and get this thing ready to sip some suds on the lake.

NOW-------having said all this-------even cast pistons in stockish everything BBCs at a lopping 4500rpm don't go "hasta la bye bye" for no reason. Something happened. From the sound of the carnage, anything you had in there would have been damaged. Something went south in a hurry. Spark, fuel, water something sudden and deadly. That's what bothers me more than part selection. That's where I'd spend my extra time and cash at this point, making sure that event doesn't happen again.

HBlair, I just went to Scarabs post!!! Nevermind the above!!!

I do agree with Derek, it's hard to go wrong with a massaged set of 049 heads for some good ol' torque!!! I love mine. Did 107% VE at 5600rpm on the dyno with a little work.

the setup you talked about will work fine, the 2 bolt main is fine also, the 049 heads are great for this setup, a scat stroker kit is not bad, make sure they ck clearances and Balance it(even though says balanced) and use forged pistons, have to really ck the AFR @ WOT to be sure not having a lean out condition, all combos are different, best of luck...Rob

Thanks again guys. Wealth of info. I'll be getting back with him tomorrow. Glad to hear the 049 heads are going to do well. He was wanting to up the compression to a little over 9:1 which sounds about right. I'll tell him about the particular brand of exhaust valve, checking clearances and balancing the crank. Again thanks.

inconel is not a brand. it is a type of stainless. i believe manley severe duty are inconel.

I'll step out again----I never use inconel unless it's a blower motor. Too much money for not enough return in a naturally aspirated motor, IMHO.

Thanks for the input. I had a little setback yesterday. I had the port motor and trans in the air on the winch, when the winch failed and dropped it all 8 ft. onto the concrete floor. Busted my merctrans I just had rebuilt. I've got a core here and after talking to Kurt at KC Marine, I'm gonna swap my rebuilt internals into the core case. My oil pan and oil pump were smashed. No big deal, they were getting replaced anyway. But my sea water pump and all the brackets got thoroughly blasted, so if anyone knows of a spare unit, I'm game.

I got that engine torn down to the bare block and took it and the heads to the machine shop this morning.