Years ago I ran an M-280-H in my 383. It was 280*duration on the intake and .484 lift. Hydrolic lifters. It had a real nice lope at idle and came on strong in the mid range. It worked great in my 68 Roadrunner with a 4spd. I would imagine your cam is more lift and obviously more duration. The old catalog I have has the replacement to the Monarch series and lists a 300H cam with 300* int. 310* exh. with 238* and 246* @.050. Lift is .530" int and .549" exh.
Hope this helps. Good luck.

Digger73 (Mike)