Well I have a slight problem. The engines both spin the same way as they are, but the radiator and air screen is in the back of the engine in the Kubota, and the Cub has a big ol' fuel tank in the way... So idk what to do about that, I don't want to relocate the fuel tank either. Thanks for answers.
I have figured out my own solution in the last couple days. I am going to install a smaller fuel tank from a Quietline and remove the firewall. That should give me plenty of room to install the engine and any other "accessories" I may install in the future.
I think your going to regret taking out the firewall. You'd be better off to mount the radiator in the front, run longer hoses, and use an electric fan. The other option is to do as I did and lengthen the frame.
Should I abandon this project? There hasn't been any work done on the engine swap, and there has to be custom motor mounts, driveshaft, and use the wiring from the Kubota tractor. I'm wondering if I should just find a gently used Command from a Cyclops to stick in it. Would most likely be a direct bolt in, and its newer and most likely more efficient.