I always used>
http://www.wallaceracing.com/accel-calc.php
which I assume to be Fly hp

according to my old actual track slips>

3000lbs '69 Cuda, stock 440SP block, 9.8:1, solid cam/2.14 906's, 850DP, 2" f/wells etc.
best was 10.7@124.8 = 484 fwhp

3550lbs '71 Cuda, stock 340, .484/284 hyd. HSD intake 750DP, hdrs etc.
ran a best of 13.29@101 = 300 fwhp

Same car with .590/312 solid, 850DP, lower gears better conv, race hdrs
ran a best of 12.49@107.6 = 360fwhp

all these figures seem reasonable to my motor specs and fwhp numbers.

Only thing with Wallace is that if you get into the very light cars or S/SS cars the numbers seem to go way out.