Hi Junkjeep....I had similar problem and I still don,t really know the original origin of my 350. There's a engine number on the driver's side of the block by the dipstick that might help. I have a Chevy repair book that has info on this ID problem. Try Chilton's on Chevy rebuilds. All I have to do is tell the parts store is that I have a 350 with the dipstick on the driver's side, 4 bolt main and that I believe it's a early model possibly 79,80. The guys know me and they look it up as a 80 chevy truck and it did good....everything fit..dist.cap, starter, exhaust gaskets etc...
I hope you find your 350's roots!!