I guess I'm not the best person to comment on the shaft and lower change out as I didn't consider just changing out the water tube and shaft etc..? Makes sense. I've only swappped out a bad one for a new one. But obviously the shaft and water tube would need to be longer and maybe the shift rod? See what the real pros on here have to say on that. As to the motor, I asked because I thought you already had a 150. Did your current 150 die on you or are you just going to swap it out for the much newer model because of the deal? If the old one is still good, then maybe buy the deal if it's that good and sell both of them and get a newer 200 or definitely one of the 4.2L F225/250 etc..? My old F225 is a heavy bastard but the new 4.2L 225/250's are 50/60 lbs lighter? Mine is ok now that I've done the mods that we've talked about but I don't think it's over powered by any measure. I hope my current power runs forever and I'd like to keep my 2120 for a long time also with paying college tuition on the horizon. That said, if I had to repower today, I sure would love to put one of the 4.2L blocks on it. Would love to put the 300 on it (same block and weight as 225/250) and prop it for low RPM higher speed cruise. Hey, A deal is a deal, I get it. Sometimes a situation presents itself and it's the best option at the time.