340 A body versus 383 B body

On the street it was a 340 by a mile. At the track stock 383's ran about 15.50 and stock 340's ran about 14.60. I had an all stock 69 Swinger 340 auto and just put a 4.10 in it on E70's went 13.70. Also stock GTO's went 15.50's with a good driver and the 351 Mustangs were about the same. I use to always baseline my cars before any changes.