Didn’t have 60s when 383 was run but was within 2.5 tenths of a well built 440 in the Dart. 383 was making right at 400 hp (118 mph 1/4
in my Duster) 1.50 60 with the 440 in my 64 on 93 pump gas. I doubt it was making 350-375 hp. Both on engine stands at the moment.