Early B3's had a lot of corrosion issues! What kind of boat? B1 would most likely provide the highest speed. I had a 1990 SeaRay 270/290 with a B1 and switched to B2 after a year. B1 was a Stallion and B2 was a Quarter horse. Quarter horse climbed the waves much better than the Stallion. SNOKING
should bolt right up. Merc hardly sells any B2s anymore. The B3 seems to work just as well on heavy boats but without as much drag. I think you could get a little more speed and better holeshot.