350 hp out of a fairly stock 340

My 67 Belvedere had a 340 4 spd out of a 69 barracuda mostly stock. It went pretty darn good.
There is 10 or 12 road test out there 340 ebody 4spds 3.55s 3.91s 14.1 14.2@98 99 100 mph lol
but those 15 second 383 4sp 355s were rocket ships
when you know you know