[Cliff R]

Here are dyno numbers from a 1973 455 Super Duty engine done here. Cam card attached. Nothing special about the engine and I didn't flow test the heads. It was recently "rebuilt" shortly before I go it but only lasted about 180 miles.

Pretty "basic" build, steel rods, Icon pistons, zero decked, didn't compute the compression ratio but probably about 8.8 to 1.

Idled smooth with a "deep/heavy" sound, made 14" vacuum at 750rpm's with only 10 degrees timing in it. I wouldn't use a cam with less than 230 @ .050" if you want to make good power with the round port heads. Even this Super Duty 455 was pretty much done by 5200rpm's. The problem with "low" compression 455's and big flowing heads is that cams to take advantage of that much head flow really start to get "soggy" at idle and in the "normal" driving range. So pulling the LSA down for your "lumpy idle" is going to hurt idle quality, throttle response and power in the "normal" driving range.

In contrast I'd go bigger with the cam and push it out on a 114LSA. We've done very well with that deal on the big 455 HO and Super Duty builds without putting domed pistons in them or cutting the heads really hard........