I'm not sure if the 912 will bolt directly into your bus, but I know you can put a 1968-1971 VW bus and the newer VW 411 type engines into a 912. Both (VW bus and 912) engines have the rear mounts (which may or may not need to be adapted or cut), 200mm fly wheels, and both are 12 volt so the electrics can stay the same. If the 912 is a 1968-69 the 'Generator' (not alternator) is actually a VW part. The other thing is, I'm not sure how well 912 sheet metal would fit into the bus engine bay (the sheet from the bus engine will not fit on the 912 engine). I guess you could do without the sheet metal but the engine will run a bit hotter.