A HR will that has the same @ .050 numbers to a HF/T will typically have 12-15 degrees more @ .200 and will "dwell" the cam at peak (unlike any non-nascar full race FT) for several degrees.

Generally the HR will have nearly the same idle charachteristics for the same @ .050 duration but will roll-on the power and respond more like a solid FT to around 6500. A flat tappet spends so little time at peak so I really look at the duration .050 down from peak to make a cam/headflow decision/comparison.

Look at Bullet cams...they have a lot more HR cams to choose from and they're pretty aggressive compared to the comps.

FWIW I ran a Straightline 252/258 @.050 HR in a 4.25 stroke 508 several years back, it had very broad wall-to-wall power and torque but had a (suprisingly) relatively mild idle that I would compare to maybe a Comp 290s F/T in a 10.5:1 440. The Comp you call out would sound pretty tame at idle...I'm sure it will run very strong... but it MIGHT not live up to your "auditory" expectations.

PS , you'll need to either go to 2" header or convert your 1 7/8 header to a full 3 1/2" header collector....the 3" collector is going to really CRUSH YOUR TORQUE and decimate your HP curve by artificially limiting your peak torque to too low of an RPM, a 3" collector is small for a 440 motor let alone a 511.