A friend of mine is working on the same project. I sold him my AN600 and he wants to put a SOHC in the rear. You would still need short axles, but you could plumb the cooling system much like the NSX and have a fuel cell where the old motor used to be. We looked a a bigger Honda motor but fear the weight would make the short wheel base harder to handle than it already is. All the suspesion is going to have to be custom, as the increased wieght and motivation is going to push handeling and stoping beyond what the stock step could ever dream of.