the adaptor plate picks the water pump up into the position it would have been in an earlier truck w/ a 216 motor. i am using one on a 261 build that i am putting in a 46 1/2 ton. i believe the pump you are looking for is a 53-54 w/a 3/8 pulley #3836084. this pump is available in a modern build through napa and rock auto. double check the pump # as i dont have my books w/ me right now.
making a short shaft pump requires pushing the shaft throught he pump body and grinding off the hardened shaft to the correct length. try searching using the pump # abaove or w/ key words such as shortened pump or water pump clearance, short shaft water pump.
big ed
