If you bore the 352 to 390 specs you will have to be very careful to follow the overbore capability. I think this can be done but again, you need to rely on the machine shop doing the work. It may be more beneficial to just overbore the 352 slightly enough to accept fresh pistons. That would mean a bore job of .017 or .030, rather than the .060 which may be taking a risk of removing too much material. You'll never know the difference on the water.
Forged pistons will cost something like $800 and Arias is the preferred brand, see George Klein and Freeman C threads, and these are provided by Gessford Machine, out your way. Not cheap, but able to withstand the constant internal blue flame of running uphill with a load all the time like a fully loaded dump truck.
Compression ration must be kept down around 8.9:1 or 9:1.
I would use a standard 427 marine style camshaft, which is a basic truck or RV torque cam.
Torque is what you want, higher horses at higher RPM are not going to be happy for very long, unless you really go through the motor with a lot of preventative maintenance and prep.
Regarding crankshaft, if you use a standard 390 crankshaft (see charts in reference links), which is the same as the one in the marine 427, then you'll end up with something like 380 or 385 cubic inches with a very slight overbore. That should give you a very reliable marine style motor, which you always want to have low compression to stay together, and I would guess it would be in the 275 horsepower range. That is a lot more power (and torque) in the boat than it was offered with when equipped with the stock 327F with 210 horsepower, so it would do fine on the water.
You can put an aluminum Edelbrock Performer (not Performer RPM) on the 352 and get some nice upgrade and much lower weight (50-pounds less) but you will be hanging a heavy circulation pump off the front of that aluminum intake and although it has been done successfully I wonder about it sometimes. Probably no reason to really worry about that one as the bolts are in shear rather than a pull-out mode.
My advice is to stick with the tried and true marine format and not try to hot rod this motor if you want to see it last for a long time and run smooth.