Hi Paul!
The chain drive is the easiest way for the transmission in this case I think. Just some sprockets and shafts, no bevel gears...
At the moment I will have to do some repairs: Tightening the sprockets on the drive shafts of the axles. They are fixed with a set screw, but that is not stron enough I think. We´ll do it with a cylindrical pin...
regards
Frank