I think you should be very careful about weight distribution. Both of those engine options weigh over 500lbs. If you hang one out back on a bracket and then put a baitwell in the back, I suspect you're gonna be real tail heavy unless you have a very large fishin' buddy who's willing to ride up front on the casting deck when you get into a heavy sea.
There's lots of good info in this forum if you search on "bracket". And there are lots of guys who've done it and can point you in the right direction. You're in the right place if you want to investigate your options thoroughly before you commit.
Dave