I'm sorry, but if I'm gonna do anything to a car that would remotely deserve the title of being called a 'hot rod', it's gonna have a bigger engine in it than what's in there now.
I agree, I did find the concept unusual. But if I was going to build it a different engine would be sitting back there. It looks like they adapted a Harley engine to a VW transaxle. There is an adapter available to mount a Ford 2.3 to a VW transaxle. I think a turbo 2.3 would make it a lot more fun.