I'm thinking about pulling the motors this winter, hour meter is a 800. They are 420hp 454's, other than dropping on a set of blowers what is the best way to increase power but keep reliable? I'm not opposed to blowers but it might be overkill for what I'm looking for. Formula 311 with TRS drives. I know it's a very vague question, I have built many SBC and a hand full of LS gen 3 motors but not much with BBC especially marine. I gave up the race car for boating, not to save money just something different. Lol

either port your heads or get a set of Dart 308's then change the cam to a roller setup I would go with some 500EFI cams and I bet you would make almost 500 hp and very reliable power!

I thought the heads on it where pretty good, I planned on sending them out to be worked a bit.

Convert to roller motor and call bob madera for custom cams and set-up. When I re-built my gen V 502, bob was the best phone call I made. If you don't make that call, you'll regret it.

http://www.marinekineticsonline.com/

THe heads on the 420 are gm rectangle port relics of ancient history. by the time you have them rebuilt and "worked on a bit" you could spend the same money on new heads the will work a lot better.

Or maybe just throw a set of 177's on and run 4lbs or so. I just have no experience with blowers, I have ran tons of nitrous and even a turbo set up but never charged.

I just saw a pair of 177s off 525sc's carbs manifolds etc on fb swap shop

I was going to have my heads redone and use them with my roller cam upgrade on my 420's. Every one was cracked between the seats. I ended up buying new in aluminum for what it would have cost to fix those old ones. Since I was on a budget I used the World Merlin III's with the raised exhaust port. There are a lot of good heads out there. Good luck

Or maybe just throw a set of 177's on and run 4lbs or so. I just have no experience with blowers, I have ran tons of nitrous and even a turbo set up but never charged.

Agreed. Bob is the master when it comes to high performance marine valvetrain. And his prices can't be beat too!

Also agreed on heads. The last set of rectangle port heads I had done cost so much to make them compatible with what I was doing, I could have bought brand new AFR heads.. (had @ $2500 into two pairs>>>)

If you're not opposed to blowers, the 420' really come alive with flat top pistons and 671's. Good roller cams (from Bob) let 'em spin to 5800, 7 lbs boost and they'll run all day! -I'd stay away from the little 177's, just a heat pump...