If you do it with a #2bolt block They are stronger lower ind than a 4 bolt.If anything .get a 2 bolt and put splayed main bearing caps on it. Now that is STRONG, JOHN

Here's my current 383 setup in my Challenger.....

010 4 bolt SBC, bored .040", 0 decked, line honed,
ESP 4340 3.750 crank, ESP 6" 7/16" H beams, Mahle forged FT's 5cc, C77H bearings, Hines Balanced
Melling Racing #10555 oil pump, Hamburgers 7qt marine pan, full length windage tray.
ARP everything,
FluiDamper harmonic balancer,
AFR 190cc heads, 73cc, further ported by Carl McQuillen Racing Engines, Lunati 73100 dual valvesprings,
Marine Kinetics "RMbuilder" custom Hyd Roller 234/240 .580/.568 112+4
Morel Retrofit Hyd Roller lifters
Smith Bros .083" wall pushrods
Edelbrock RPM Air Gap port matched to AFR port
Holley HP 750 DP 78P,88S Jetting
Lunati Voodoo Widebody 1.5 roller rockers
GLM aluminum manifolds ported
FastGlass Stainless 22" long dry risers
Full MSD ignition setup, coil, wires, dist, 6AL,
10.07-1 SCR Engine makes 475hp @ 6000rpms

Idles at 750-800rpms neutral and I can lug it down to 600rpms in gear idle. WOT is 6000-6300rpms depending on weight in boat and air temp. Boat runs 78+ all day long and best I've seen is 80.5GPS @ 6300rpms.

http://www.youtube.com/watch?v=rxT0vfMSJDM

I would contact Bob Mardera "RMBuilder" of Marine Kinetics and have him spec an engine combo for you. He's the "MAN" when it comes to performance engine combo's. I'm more than pleased with how mine came out...

As to going with splayed 4 bolts and all that..... For your setup it's way overkill IMO. I've never needed more than a regular 4 bolt with good ARP bolts. This 385 spins 6300rpms and my old 355 solid roller spun 6600+. It is cheap insurance though if you have money to burn.

I ran a stopgap 360ci SBC for a few seasons. It was a fully stock GM shortblock. Cast everything. Topped with my topend. Ran 365hrs @ 56-5800rpms. No problems what so ever. Upon teardown it looked great inside and I put it back together for a spare shortblock.

NOW we are getting somewhere. Thanks Ryan, have seen the start-up on Tube before. 80vs65 is AWSOME. How long have you had this set-up in service? What changes if you were to do it over? Is that a B-1 outdrive? With all the input starting to come in, i'ts getting exciting. THANKS R.M.

How bout it DAWG. Any of this starting to sink in?? R.

Thanks for the compliments man... I built the engine over the 07 winter and installed in March 08 until now. I've logged 163hrs on this engine and as you can see I don't run it easy either. I would say 50 hrs easy at WOT or above 4500rpms. I can cruise @ 3200rpms @ 42-45GPS with the QIV 4 blade hardly burning any fuel per say.....
Only changes would be a bigger cubic inch SBC... Dart or World 400 based aftermarket block 406, 414, 427 etc.....
Only reason why I didn't is that I am running an Alpha SS 2.5" shorty drive and figured I'm way overpowering it as is.

Just my opninion, but I've had a friend that bought a crate motor a zz383 which already comes with brass freeze plugs, hypereutectic pistons the new style powdered metal rods, moderate hydraulic cam and aluminum intake plus aluminum heads. could be the ticket with use of a uscg approved carb and ignition rated at 425 hp I believe the going price $5200.00

why are you swapping to a bravo? If you take it easy on it like you say you are going to an alpha can hold up to that kind of hp for a long time.

Thanks for ALL the input. Entire rig is 21yrs. old. Time to replace a lot of STUFF. Engine, outdrive, controls and a few other componets. With all the knowledgable people on this & another site I hope to pull this off without a lot of headaches. Thanks again. R.