Hi Bob
I did more than my share of clutches in the 70's but I don't remember that van set up
but I have to check my name tag every day to know who I am. I know the 60's and 70's trucks up to 3 ton with the 250 and 292 used a left side mechanical clutch. I'm with you when you say it would make a good conversion.. I have been watching for a 292 for years to put in a CMP. A 63 or 64 Chev powerglide is real short and I think they would work well. 64 was the last year for a rear tranny pump also so you could push start them. In 65 they went to a longer tranny and no rear pump. I would love to make one of these up to drive to CC? or BB? Who cares if it's not 100% original driveline. At least you would be showing up with something you drove there. My opinion on this changed after spendng time with Preston Isac and his diesel LAAT. When he pulled out of Portsmouth heading for the ferry to France in 94 and actually accelerated down the street towing a Bofors, Brian and I stood there in awe.
Cheers,
Barry