What you're saying would be right for a 1968 motor. But what you're telling the guy is something that ain't right about the motor that's in the car he's looking at. It's not the original motor. It's not a 350 HO. It's not even a 350. You won't need the PHS docs to confirm that.
Did you notice he posted the partial VIN number? It's from 1975, not 1968. The 1975 YM is a 400. Its NOT a 1968 YM 350 HO. The casting number will be 481988 (early), not 500557 (and not 9790079).
Saying it was a Bonneville motor was just a guess. As it turns out, it was a bad guess since it came from the old Kansas City plant ("X" in the VIN). 1975 production there was A body cars, so that makes it a LeMans or a Grand Prix engine - not a Bonneville engine (as I assumed originally).