carb issues

You may have too much timing in there. Take it up slowly through the zone between 1800 and 3800, and at ever-increasing throttle settings, first as a 2bbl, and then as a 4bbl.
Or simply back up the timing about 8 degrees and retest. If it's cured add 2 degrees and retest. Repeat until problem returns. If it makes no difference, put it back where you found it, and switch to carb tuning.
IIRC ,I'm running 76/84 in my 360 with a slightly smaller Hughes cam; 230/237/110 at 900ft

And I totally agree with MD on tuning the front by itself. And for a streeter,I try to put a PV in there that will stay closed for as long as possible without compromising driveability.If I need a tad more pumpshot to cover the hole, so-be-it.
FWIW; I have bought several PVs of various closely spaced ratings. And when I roadtested them, they didn't make much difference. So I bought a PV tester, and the truth came out.For the several brand new valves I had purchased, The calibrations were very,very similar. If you ever wanna get the low speed circuit really dialed in,like for fuel-mileage(as if with that cam), that tester will save you hours of needless roadtesting