If someone is willing to give you the engine, you take it! You figure out the specifics later.
There are several off the shelf adapters out there. I purchased one for a club car XRT1550 with the Kubota D722, took it to a machine shop, $95 later, I have a 1", 1/4" keyway stub shaft adapter for my current build.
Check out these guys:
https://www.hayescouplings.com/produ...e-stub-shafts/
They will even custom make an adapter for you.