I think if you could address the cooling needs, the mounting and transmission of engine power to transmission that you could probably do this fairly easily. I bet it would have a very distinctive sound as it went down the road.
I'd love to see it, it would be like the Changzuki guy only kicking it up a notch! and unlike the bike, you could stay dry inside as you drove along in the rain.
It would be EMP proof for the SHTF folks - yet another selling point.
Go for it!
RC