Try calling Edelbrock tech support. They have a virtual engine dyno and the guy will plug in your specs from your original cam. Then ask if a performer RPM cam will help, roller or flat tappet. I respect them because the waived me off on two separate calls: 1) Will an Airgap be a good expenditure. 2) would their performer RPM roller cam be a good expenditure? Both times they said the difference would be negligible and not a good use of money. Impressive!
I have been very happy with the RPM system, very flat torque curve on a 351. Pulls hard from 2500 through 5500 before gently rolling off. Still pulling very hard at 6000 when I hit the rev limiter. Cannot tell you how many autocrosses a year I run the last gates with the rev limiter in full action.
I run a 4150 650 Double pump which gives amazing throttle response but is a gas guzzler. Its made for racing - the Holley performance book suggests vacuum secondaries for any street car. They are great for set and forget for years.