Have you checked on the Tower 61 or 75? Both would be great motors for the 4*. I plan on using a ST 90 in mine, but that's a little overkill.

Magnum is another good choice (61, no longer have the 75), and so is TT, however I do not have experience with the TT's.

Tigershark? GMS? Man, there's lot's of choices, eh?

New or used?

Gary