In the late '60s and into the '70s, a friend raced a Boss 302 in the TransAm series. Race regs mandated carburetor max size by throttle bore diameters, which came out at 830CFM. Holley built a secial carb for TransAm. You could purchase one through Ford and GM performance outlets, over the counter. Naturally being for a special purpose and limited production, they were expensive. The factory teams could afford this but many private teams could not. The next size they could use that was commonly available was the 780 CFM. Being commonly available it was fairly inexpensive. John's team admitted to giving up a few HP by using the affordable carb. Never found out how much, but they ran mid pack much of the time.