Mark,
I have replaced severely cupped lifters and lifters which were pitted without replacing the camshaft (didn't want to but had to!). They worked fine, even if it is not the best practice, but- only after a close inspection and mic'ing of the cam. If you don't have clean even wear across the cam all bets are off and looking at the lifters you may not have even wear. Do you have the same spings all the way across the heads? You can change the springs to a liter set to insure good lifter rotation. In a marine motor you shouldn't have to worry about valve float. It should at least let you finish out the season. Do you have the same amount of hours on the other engine? AHHHH
