5200 will be fine!!
You might want to look into a composit transom?? I have never had to do a whole transom before?? But the composit looks to me to be the easyest. What you do is open the top of the transom by cutting it open, then you use what ever tools you need to do to dig out all the rotted wood. After you have it all cleaned and ready to go you mix this to part composit and pour it into the empty hole you have now made, After it has dryed you can drill it for you new motor mounts and you now have a rot proff water prof transom.
Of coarse this is the short version of the project!! And you will have to read all the steps to doing it.
I was going to do this to mine if it came down to it but I was lucky to have to just fix the hole were the outdrive went thur.
Here are some links: The first one tells you alot! and how to check for the bad transom.
http://www.islandcoastboatworks.com/...a3_article.htm
http://www.transomrepair.com/
http://www.tikiwatersports.com/jobs/transom1.htm
http://www.odayjavelin.com/Transom.html