I built a LT1 back in the 70's for a friend, it was his dream motor. Early 70's 4 speed Camaro high gears. Chevy NOS short block, angle plug iron heads, crummy valve job by his uncle, insisted on using the worthless plastic toothed cam gear and OEM HEI distributer. My 273 would beat it. A couple years later, I saw it again. He had given it to a cousin. You could hear the valves leaking, an absolute dog. A 170 slant six would beat it. The LT1 might be fast in a race car, with race gas, tuned to the max, but not fast on the street with pump gas.
Many 340 cars were faster than 14.7, my 71 Duster included.