Well I'm going to do the swap and see what happens!
Basically I have 2 of the same boats. I took out the new one only once this summer and I can really tell the difference in control of the B1 vs the B3. Control of the boat is much more responsive with the B3 at slow speeds(docking, etc.). I figured that I might as well swap them. Doesn't really cost me anything.... I've owned the 2004 B3 boat since new so it doesn't owe me anything either.. lol
Just some back story if anyone is interested:
A couple years ago the block developed a crack over the winter. I always drain the water but I suspect that the one way drains on the side of the block are clogged and all the water didnt drain. I JB welded the side and its lasted the past 2 years. The boat actually still runs amazing and doesnt leak water. At the same time the interior upholstery is not in the best shape and I've developed a leak of drive oil somewhere behind the engine that drives me nuts because the bilge gets coated with oil. I suspect that its the 90 deg fitting but I cannot access that area without pulling the engine. Its VERY tight on this model.
This summer I bought the 2006 B1 boat that has very low hours with perfect upholstery. Its almost the same boat with a few upgrades. Only down side is that its not quite the hot rod my 6.2 B3 is.
If the swap goes good I'll probably put the 2004 up for sale. Probably wont get much with a cracked block but thats just the way it goes.