Some might frown upon the modifications, but whoever owned that tractor needed it to use, not tote it around to shows on a trailer.
If that tractor was in my possession, I would leave the transmission in it, install a K-90/91 Kohler , and get it moving under it's own power.
If it works well, do a little cosmetic work and enjoy the heck out of it. I don't think there's anything wrong with having something unique that will stand out in a sea of shiny red tractors.
Some of the best ideas and inventions came from backyards, garages, and farms...... and that includes Wheel Horse tractors. Just because it's not Elmer and Cecil's history doesn't mean that it's not worth preserving. :USA: