I ditched the idea of the old 1 5/8 shaft in favour of a new 1 1/4 one. The old one is of questionable quality and doesn't fit through my lathe headstock to check if it's straight. The shaft will be supported with two bearings to minimize whip and another at the front pto mounting plate. Don't really know if 36 hp could cause whip, but easy to avert problems. A simple ladder frame, 2x3 x .125 box tube, attached to the chain case and a couple of bolts at the front. A fixed mount on the front will allow quick mounting at the front end.
The pto shaft concerns me a great deal. It will run between the loader cross braces with not much wiggle room. Won't be a problem with minimal loader elevation, don't see a happy event with curl though. Have to figure out what kind of travel limit options I need to put in place when the time comes. Unfortunately my Cardboard Aided Design system doesn't allow for 3D animation.