used motor for 20 MA?

[CaptCurt]

This is along the lines of a couple other threads in this section.

I am going to put a new(er) motor on my 20' Master Angler project. It currently has a 175 Merc (1979), which I have decided I don't want to fool with repairing. I am looking at several used motors, most of which are 150's. For the kind of water I'll be in, I don't really think I need anything over 115-ish.... but I don't want to under-power the boat.

What is the smallest motor I should put on a MA? Any specific motor recommendations? My price range is under $4000 if that helps any.