It looks like a HD Dyna engine would fit, especially as the cylinder angle is less and should fit between the suspension. There seems to be some debate if its legal to out a less compliant engine in, you wouldn't get away with it in a normal car where the MOT checks emissions. As they dont in the case I guess you could even fit an old shovel or pan - albeit it would be leaving a black line on the road!
If a counter balanced Harley would fit that would be great. I do not know if the current S&S engines are better balanced than the Xwedge but maybe so.
I suspect the first person to make a conversion kit for the USA folks ,who probably have less stringent inspections if any at all, will sella lot of them.
