Scotty,
I'm sure if you call the guys I listed with your engine size etc. and question them as to which way the arm comes off the back of the pump (straight, down, up) they will give you the correct answer. They are there to help make a satisfied customer - not to rip you off. Gary at Roberts, Chris at Bernbaums, and not knowing any one person at Vintage Power Wagons, I can say these guys know what they are talking about/selling and want to help out. After all they need return/our business, how many people are going to be asking them for parts for our cars (a finite number) need more parts down the road (no pun intended). Therefore I would pick one to trust and ask questions and go from there. Besides if Ol Andy were still there - even he would be helpful even if a little gruff (he was known for that by some people)over the phone. Its important to connect with a supplier you feel conforatable with, you will probably need more stuff/parts again.
Tom