Re: What should I repower with??
Okay, to answer a couple of your questions:
Yes, a 350 would work, with some re-proping, however, you need to factor in the cost of the manifolds. You cannot use you're 4.3 exhaust manifolds on the 350, so you would have to factor in the cost of replacements.
The most desirable truck 4.3's are 1996 to 2001, because of their cam's and their balance shafts. Having said that, if you don't go with the same generation as what you have, some of your stuff may not bolt up.
For example, the 4.3 came with regular heads and "vortec" heads. while both engines had the "vortec" name on them, only those made after a certain date (1995 I think) had vortec heads.
The vortec heads give you better torque, HP and fuel efficiency, all things being equal, you WANT vortec heads. Problem is, vortec heads have a different intake manifold bolt patter. So if your old heads were non vortec, and your new heads are vortec, than you will need a new intake manifold.
Also, the bolt pattern for the oil pans has changed as well over the years. I'm actually running a 4x4 truck cast aluminum oil pan in my boat because my stamped steal marine oil pan would not bolt up to my newer 4.3.
If a guy in this forum with that many posts is telling you to sell the boat because it's got a yamaha leg, I'd do it. Used boat ownership is all about cost of ownership, and I think the point he's trying to make is that the Alpha's are much much cheaper to own.
Might make more sense for you to swap the correct 4.3 in and sell it. If your existing engine doesn't have vortec heads, than you may have to source and older 4.3 truck engine, and it may be harder to find with with low milage.
