I wouldnt necessarily trash the scooby - at a bit over 70hp it may not really have enough power, that would need some sums to be sure, but it is bulletproof and a nice low revving engine. The installation is poor though - check out that radiator (why do we not use smaller twin radiators mounted either side of the engine at an angle, with ducting to facilitate airflow? Could be very elegent). If the Scooby's not man enough, my choice would be a K series even if its a bit heavier & needs a rad.
But looks like an opportunity to get a worthwhile project.
Ian