I think that most of us fall into this dilemma at some point. No matter what your limit, it is easy to get there. My son Kevin and I have in the area of 80 motors currently. This is really too many for us, but that still didn’t keep me from bringing home a KF-5 and a KF-7 from a recent meet. 🙄 The thing is, I already have a KF-5 and KF-7! The KF-5 needs a lower unit, and was cheap. The KF-7 is a 1950, my other one is a 1949, (The only two years they were made). I would really like to send the KF-7 to another home, we will see. We seem to find that getting more than 25 motors on the water each year is a challenge, so adding more will them not make this any better. I love to build these things, often from parts or from total hulks, so that is a lot of fun. The problem is finding time to run them and keep them in good serviceable condition once they are restored.
I have several motors that should be redistributed to other collectors or fisherman. I plan to finish the restoration of a couple of 110’s to send to family members, so that should take care of two of them. I really don’t need three KE-7’s, even though they are 47,48,& 49 motors. Two KG-7’s, 50 & 51 two KH-7’s, 7 Mk-25’s….you get the idea. I am trying to rethink the 5 motors in the Scott Atwater/Corsair collection. Fine motors, but kind of out of my Mercury focus, and perhaps they could be better served elsewhere. They are safe now, but do take up space that is hard to come by. And even with all that said, I freely admit that I am actively working to acquire some parts to assemble another 1974 Mercury 200! 😕 
Steve