Welcome Carl, I agree wit CBE.

Before you buy a motor, THOROUGHLY check out that transom for rot.

If you need to repair the transom, then you would be much better off using that jack plate money to restore the transom to take a 25 inch shaft while your at it ( of course MJ WOULD TELL YOU TO MAKE IT A FULL TRANSOM AND HANg YOUR 25 INCH SHAFT ON A BRACKET ;D, BUT THAT WOULD COST MORE).

If the transom is sound, you might be able to get away with a 20 inch shaft - depending on how and where you will use your V20.