Hmmmmm. CPNE's setup uses a combination of later model (wider spacing on the bottom crank pulley grooves) and other pump setup, which is running off one belt. The original had two belts and close together.
Here are three setups that I have put together that fit our closer/original crank pulley. You may still have to run one belt or two depending on which pulley groove you use. These were checked on a 70 250 pu engine.
http://67-72chevytrucks.com/vboard/s...hreadid=108987