How about compromising. Sell the engine you have, use the proceeds to help buy a >2000-yr drivetrain, all while keeping an eye out for an electric donor drivetrain.
It all comes down to priorities, how badly you want to be driving "something" now that may not be perfect, versus waiting for perfect to show up. Personally, I've found that waiting for "perfect" can cause the entire project to never happen.
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Midlana book: Build this mid-engine Locost!,
http://midlana.com/stuff/book/Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from
https://www.lulu.com/