Do some research. late 60's Chevrolet swapped out the 396 for a 402ci (6.6-liter V8) engine while retaining horsepower and the SS396 (emblem 396) model designation. Also released (mid-year) was a new top-of-the-line engine, the massive 454 big block (7.4 liter V8), available in LS5 and LS6 versions, producing 360 and 450 hp respectively. Equipped with this engine and compatible 400 trans and 12 bolt rear-end combo, the sedan pickup managed a 1/4 mile time of 13.44 seconds - at a speed of 108.17 mph. A few guys are restomoding, the 69 and 70's models with LS3's, and RoadsterShop chassis. Sweet ride and all the benefits of a modern vehicle plus easy to maintain, and if you want more power, bigger throttle body, or add a supercharger along with rods and pistions and different cam.. .