Sounds as if you may have a vacuum leak in the brake line or booster.

I had a solid 6" with a 245/517 cam and a vac gauge plugged in the rear carb port. Found that my brake booster and fitting was causing stumbles and misses on acceleration but didn't have an issue (other than no brakes) running with rear port capped. I can't say for sure if this is your issue...but.

High lift cams will always have low steady readings if rest of engine is within parameters.