You might have missed it but the truck is a Frankenstein, nothing is original. I did google already as u mentioned butchad no luck. I scored with Ebay, looks like a 64 Impala voltage regulator.
I cant wait to see what else Devil Dog was rebuilt with 
Frenchy, I would bet you could use any mid 60's regulator on the "dog"! Does it have an alt or is it a generator?
Nice thing about those old beasts is the mix and match you can do,I think you can scavenge old GM electrics to get it up and running.
I haven seen a 345 in about 45 years,make sure the distributor is still openning and closing the points,but you knew that!!!!!
