Need help trying to figure out what this carb goes to

I bought several carbs from a guy at a swap meet once. It was very obvious he had been hitting the bottle early that morning and he was self-professed drunk. He was selling all of them for a $1 each. He was standing on top of his trailer with a carb in each hand held up in the air yelling "Come and get it! One dollar a carb! I don't want to carry this **** home!" I grabbed all could carry.

I have a Holley 4 brrl with vacuum secondaries.
Motorcraft part number E1UE RA A2A29.

I know its for a 1981 Econoline van, but I can't find anything to tell what motor it was probably for. Suppose one of these is worth building? How can I tell what the CFM is?

if its for a van, its probably for a 460, and likely 600-650 CFM. The 351 ho was available for econolines, but not in 81 IIRC. There should still be a holley list number on the choke horn.
[addsig]