My only experience with that engine was on a chartered C&C 27. While it always started it certainly seemed feeble, even on a 27 footer. Only thing I liked about it was the quiet vibration free operation. If you got 12 grand... And you are going to keep the boat... And you plan on refitting everything anyway... May as well do it. Think not only about your engine, but the drive
line too. Cutlass bearing, prop shaft, engine controls,
propeller. All that stuff is wearing away... That A-4 and it's associated friends are going to nickle and dime you forever. Might as well spend the money on an entirely new package and be done with it.