I would lean toward too big of a motor, that's what throttles are for, if you have too small a motor you have to buy a bigger one then put it in, never as neat as the original installation.
I've been thinking along the same lines. I'd hate to put a 38 on it and a couple years down the road, with floats or towing, find myself shopping for another engine.DLE55 has my attention. The hobby shop I was just at had one on hand, at a discounted price... Hmmm...