Transom replacement on 14' Gregor. Easy?

Ist of all I'd like to say this appears to be a great site! I have a 14' Gregor and the inside is like new, seats, spray on bed-liner, carpet, downriggers, FF etc... While not as tricked out as some of the photo's of boats I was looking at on this site, it is perfect for me. I recently noticed the engined mount screw plates were pushing into the wood transom as if it were kind of mushy. It is sprayed with the bed liner spray but I believe it is either plywood or partical board I would love to post a picture but not sure how, so I will try my best to describe the back of the boat. It is pretty typical. Directly below the motor (on inside of boat) are two braces which angle down. The bottoms attach to the floor (welded) and the backs are bolted into the transom. I will quit rambling here...because I can't remove these 2 braces, how hard is it to slide the new wood down in there between the brackets and the top lip? The back wall of the transon (the aluminum part) goes to the top and then is currved around the top of the wood. This 'lip' cannot be removed or bent. Just by looking at the area, it seems like this may be a real project squeezing the new wood in place. I'm really sorry about no pictures, but I'm not sre how to do that.
Also, I read somewhere on these boards not to use pressure treated wood up against aluminum??? Is that true? Whatever wood I use, I was thinking about notching out an area (4" X 10") with a router and placing a 1/4" aluminum plate in there where the motor screws go. Any thoughts on that?
Thanks in advance! John

I un-bent the top lip then bent it back. Others have cut the top off and replaced it with a custom made top cap.
Pressure treated wood is a no no use a couple of layers of exterior grade plywood glued with Tite bond III.

Thanks for the reply! I do have a possible solution but am wondering if it will effect the stability. Instead of replacing the transon with a full sheet (approx. 5' wide by 2' high) what if I replaced it with strips of ...lets say 5' wide by 6 inches high? Like a 1"x6"x5'? Follow me? This way, I could easily slid these down in between the transon bracket supports, instead of trying to force a larger sheet of wood down between the transon bracket and back sheet of aluminum. By having the transom wood split up in several horizontal pieces, is is still going to be have the strength needed? I know I'm not dealing with the torque of a 250 hp motor here :lol: but still...

It wouldn't have the strength of one piece.

I also have a 14 foot Gregor. Mine has a splash well and and the wood is still good so far but I did look and noticed what you mentioned about replacing the wood. My first thought was to cut both angled braces but leave enough above the floor to bolt on some new ones.