Welcome!!
No such thing as overpowered with a 225. I almost powered my 83 V20 with a 225 Optimax. My main fishing is offshore, most of the time 20 to 35 miles out. The V20 is a great all around vessel. Before i took her out of comission for some repair work, not only was she a offshore fisher, she was a family boat for watching fireworks, going to the beach, cruising, etc. Alot of our family memories are on her.
Simple transom test is to tilt the motor all the way up and push down on the foot watching for transom movement.