Carb issue?
BTW
If you are attempting to tune to a vacuum number, with the 7177 cam, you are in a world of hurt. Because it will lead to a massive amount of idle-timing.
I rarely use a vacuum gauge to even observe the idle-vacuum, of an engine with a performance cam.
At 930ft elevation, my 367cuber will idle down to 550 in gear (10.97 starter gear) and pulling itself with no clutch slipping, at 5*advance, with an ancient 750DP @10.95Scr and a Hughes HE3037AL cam, that is advertised at 276/286/110 and .050s @ 230/236. I have absolutely no clue what the vacuum is and don't care, because the T-slot setting allows lots of tip-in without a sag/hesitation.
This same 750DP has been on all three iterations; 292/292/108, 270/276/110, and the current 276/286/110. Only the 270 cam did not require bypass air; Having come from the 292 cam, I did have to solder the holes closed. Going to the 276 cam, I had to provide the bypass again.
Just saying.
BTW
I should also mention, that using KB107s, in at the minimum skirt clearance, and the rings gapped as per the street spec , I had overheating issues with both the 292 cam, and the 270, that I could not solve in the usual ways. So I took the engine apart and added a smidge of skirt clearance, and new Plasma-Moly file-fit rings with quite a more gap. That got rid of most of the heating issues.
At this time, I also noticed a change in the engine's personality, so I retuned it. And that was the sweetest engine I ever had. I was very sad when, about four years later it dropped camlobes right after an oil-change. And initially, a little disappointed with the one-size bigger Hughes 276 cam, that I had then installed.
The point is,with the tight gaps, the engine had been working hard just to idle. After I free'd it up up some, it was a much happier engine. That 270 cam would tic-over effortlessly, at the new assembly spec.