Re: AQ125 motor mount
You could possibly fab a "stringer" that is contoured to the oil pan, epoxied to the hull/bilge. Of course, you would want to epoxy some sort of block/base down first to distribute the load of the stringer.
Otherwise, you would be looking at some metalwork to be able to "bolt" the engine down. (or up, in your case )
I noticed when I replaced my impeller 2 years ago the holes under the carpet in the bulkhead didn't quite match up, and had to pry the engine up a little to get proper access. Of course, 27 years will do that to a transom....LOL