340 improvements with dyno numbers

my '71 340 cuda> ran 12.39@108mph in 3550lbs.
stock 340 Xheads no porting, fel-pro blue gaskets..9.5:1 ?
Holley strip Dominator, 850DP, 1.75" Chassis in/out race hdrs
DC .590"/312 sft cam, MSD6A etc. = 370 fly hp, ran strong

391hp from that combo?, not impossible....probably made more CP than I did.