engine wise depends what you want mate, the later intercooled TD mk6 Escorts go pretty well, so could fire one of them in, or could zetec or RS2000 it - again both were found in mk6 escorts so a fairly easy conversion - just buy a donor car.

I think personally i'd be buying a scrap 5dr Escort GTi cos you'd get the engine and box plus all ancillaries, the half leather interior (you need 4dr doorcards on a van), front fogged bumper, sideskirts, 15" wheels etc etc