After my ancient (1977) 350 threw a rod and destroyed the engine I started with a low compression (regular gas) 350 (5.7) long block crate engine directly from GM. As I recall 15 years ago that was about $1400. I had compared the part numbers and except for the pistons, heads and cam the low compression model was the same as the higher power units. My primary activity was fishing (actually trolling) so idle characteristics were very important to me. I had cam data from a previous rebuild where I had sent the old cam to Crower for a regrind years before so I just ordered a Crane cam (Summitt) that matched it as closely as possible.
The hot rodders will tell you that you want a 4 bolt main (stronger and more $) but my original boat engine was 2 bolt as was the one in my 1974 Blazer. Not that I have any real exposure to it but I’ve never heard one of these things coming apart because of bearing cap issues. Guess I would try to duplicate what you have now.
I took the new engine home, replaced the cam, put in brass freeze plugs, installed a high volume oil pump, roller timing chain, and put on the marine windage tray and aluminum pan from the old engine.
The original engine was opposite hand rotation so using the automotive block involved a new prop and reconfiguring the velvet drive to turn the other way – as I recall this was just a matter of turning over a ring under the input shaft bearing.
She hit the WOT specs on the money.
The opposite hand rotation was also what drove me to the previous regrind by Crower vs replacement---I just couldn’t get the backward turning cam reasonably. Interestingly, the wrong way cam was turned by gears vs a chain so it turned opposite to the crank – or in the same direction as the automotive engine. The significance of this is that the original distributor also turned in the correct direction and didn’t need to be replaced.
My guess is that the backward turning engine in a single engine boat was an effort to keep the production numbers up to support the twin engine guys. I think the diesel guys just turn one of the engines around to avoid aggravating the torque issue. I don’t know if the gas guys are still building backward turning engines.
GM has been through several iterations of the 5.7 and you need to watch for things like dip stick changes (which side), single one piece rear main seal (good if you can get it), pan changes – where the pan meets the timing chain cover, intake manifold and valve cover bolting etc. I’m also not sure that the newer blocks still have all the old bosses and bolt holes for mounting things – engine mounts, fuel pump, alternator etc. As a general rule it would be wise to get an engine that is the same type and vintage as your old one and hopefully all the old accessories will still fit.
Good luck…..