What they said. I did it with a Mag12 into a 71. Didn't put a PTO on it because it's setup for plowing. Here is the thread on the build.
http://www.onlycubcadets.net/forum/s...ad.php?t=20585
Clutch or engine removal is a PITA because of the deep sump on the Mag. You cant slide the engine forward to get it out or in, you have to use a special coupler from Midwest Super Cub or slide the rear back.