The 383 in the Charger is nothing special but pretty strong. Mike McCandless built it and ran it in a 3500 lb. RR for a short time. I have most of the specs at home but what I can remember is it has Ross 9:0-1 pistons, Comp "540" cam, 906 heads, balanced, and a Performer RPM intake w/ a 750 Holley.
IIRC, best ET was 7.15 in the 1/8th with a 4k converter (never thought to ask what gear).

'71 Charger 383/727
'17 Challenger SXT (Wifeys car wink )