Re: Need advice on rebuilt engines usengines.com...
Heard a lot of good things about Rapido. Not sure if they still do, but at one point they offered a "no questions asked" warranty. I don't think they offer a 383 though.
I called US Engines when I went from 350 to 383 and it seemed like I caught whoever I talked to having a bad day. Gratuitous use of what I call "marine engine mystique". But like I said, might have been a bad day. But do check their warranty. Warranties have a way of having prohibitive terms and conditions. Especially since many engine failures aren't actually a problem with the engine itself - somebody failed to winterize properly, didn't keep an eye on the exhaust system, overheated, etc. and most warranties don't cover failures from abuse or neglect. Which are two very broad and subjective terms.
After I looked at a bunch of different places online I ended up finding a local shop and don't regret it. I found that local shops I talked to gave better service, more feedback (as to what I was trying to do and the best way to do it), and turned me on to good parts at very competitive prices. You might be surprised how much motor they can build for $3200 if you get everything through a local guy.
No matter which way you go, also be sure to ask what they're using parts wise. Are cranks new or turned down, and if so how much? What is the maximum overbore they use? What internal parts are cast or forged? Is the rotating assembly balanced? You can get something that runs without every aspect being ideal (since you don't need a drag racing engine), but if you get a gearhead buyer at some future point being able to converse about the specifics might be helpful.
But check into the warranty. 7 years is hard to beat if all (or a substantial part of it) is "no questions asked". Otherwise, if you can find a quality shop locally you know you can always go in and talk directly to the owner if you ever have a problem.