[BuB-44]

No problem, just throw in 2 rear hub motors like these and attach an appropriate battery.
Peak power of 30 kW provides sufficient acceleration, and with 15 kW permanent you should be able to go almost 50 mph.
No gearbox or clutch needed

 

[BuB-44]

Hub motors are just a quick and easy way to get going, without the need for machining.
The bearings may need a better seal, maybe from a quality manufacturer - at a fraction of the effort, compared to a engine conversion. They are quite costly, though, compared to a used DC motor.