Gotta go with Dave here - he is spot on. As I'm probably of your dad's age, I can tell you that the Holley double pumpers were a rage in the 60's. If asked, we could never have justified or explained "why", but it was really cool to open your hood and show off that big Holley. We saw a ton of them on boats (Lake Arrowhead, California) - but that's a whole different story as water is a bit different than pavement with a sudden slam to WOT.

Vacuum secondaries are your best bet here unless you want to get into some serious transmission modifications and a higher stall speed on the converter.