340 cam in a 318

I’ve seen 1 318 slow down. My friend took his Challenger to a Speed Shop. Added headers and dual exhaust. Street Hemi grind cam. 2.02 X heads LD340 intake and a 625 Carter afb. Spring kit in the distributor. It had 3.23 gears. Traction bars. 2bbl form it ran 16.1. With all the mods it ran 17.4. This was in the late 70s. Kim