Only gk73a cams will fit in a B4, gk76a are different diameter. B4 and Gk73a share the same exhaust cam (pre 93) and slightly different inlet. I'd be supprised if swopping the cam would make a big difference, more lift will help up top, but inlet's is where the most power is at, for example the 1st gen vvc bandit had variable inlet and exhaust cams but the 2nd gen only had inlet as the power was as good.