I would either keep an eye on ebay (not very often one comes up) or ask Marlin if they know of any.
Something like mine it sounds like what your after. Engine conversion (after blowing up the other one) on an already SVA-ed car. But I'm not selling.
Depends. When I was looking at building a car, I wanted the whole experience from the start.
Or buy a ready made one??? Big Rich's is still for sale.