If you do not decide to supercharge what you have, then just sell it and start over. You will not make close to 600 hp with a 454 NA. If you put a 4.25" crank in it, you will also need rods,,pistons, heads, cam,intake etc. What are you going to reuse........Not much. You will take a running engine that is worth a few dollars and turn it into a pile of used parts that is not worth much. You could make 600 with a Whipple or Procharger on your Mag, or you could start over with a 540 NA and make 600+. I would not build on what you have as it will cost you more in the long run. Hope this helps, Eddie.

I agree with Wahoo. Sell what you have a buy used fully marinized Merc 525's (really 540-550 HP) They will be turnkey, reliable and low installed cost. If you get to 600 HP, you are only leaving about 3 MPH on the table.
What do you want more...the "hunt" or reliability?

http://teaguecustommarine.com//store...products_id=28

Look under "Specs"

That teague motor sure is impressive. Is it possible to have a motor like that with efi or does that mean alot more $$$? Is efi really that much more reliable than efi?

bore your 454 to 468, use a dished piston, .700 lift solid roller cam, intercooler, and cheap ole 250 blower and you will be close to 700HP. The thing is, unless you can pick up all this stuff from a swap meet etc at a huge discount, it is cheaper to order a long block from one of these guys here on the board or just mail them a check for 11-15K and have a bolt in engine.

Remember though, that going from the 454 that you have, to a Dart or Merlin 540, none of the accesories you have will wrok except maybe the sea pump etc.

You will need oil pan, valve covers, just about everything will end up being new.

If you are going to commit to it, then sell the 454 in one whole piece unmolested, and just start from scratch.

Good advice. You mentioned crate motors. Start with this:
https://store.gmperformanceparts.com...rate%20Engines

$12,350 add a marine components---oil pan, starter, carb, flame arrestor, merc/sierra intake thermostat housing, exhaust, remote oil filter (don't forget the oil bypass conversion) and larger marine oil cooler. Add the marine accessories that would not changeover from the 454.

I believe that block already has brass freeze plugs. Valves? Hey, run good fuel and don't rev/run the snot out of it, you will have a solid powerplant for many hours.

600+ HP and plenty of torque for under 20k.

Forgot you have to loose the flexplate and purchase a steel flywheel. Don't forget your MSD 6M w/built-in rev limiter.
This is the block specs.
https://store.gmperformanceparts.com...umber=25534368

ZZ572 motor already has the roller cam and roller rockers. Depending on your marine exhaust choice, may have to purchase different valve covers.

If you are talking about your motor, you do not have a Bowtie block. If you have a Bowtie block laying around you can bore and stroke it to a 540 and as others have said you can easily get 600 HP. Contact Ateco in Waukegon IL. You could work a trade with your engine or sell it outright. They can build you a 540 with the HP you want and do it for about as reasonable as it is going to get. You will need headers, a carb, larger oil cooler and a new prop. You will love the difference.

These GM crate motors are definitely sweet. However if you notice at the bottom it say's "Not intended for marine use"

Yep, they do say that. But I ran my ZZ502 crate for 4 seasons without a glitch. Now it's a 557!!