rejetting holley

Its a possiblity. They seem kinda close together. there is a possiblity of something else being the problem. But since you asked for carb advice I would increase the secondaries to about a 77 and see if it changes. I was kinda having a 2 fold problem that ended up being something else. The car was getting hot and preignitioning (but silently). I went with a higher octane and fixed my cooling problems (had a partially sticking thermostate) and it went away. The best way to describe what I was dealing with was at about 4800rpms at full power it would almost fall on its face. Felt like it was missing..but not consistantly on one cylinder like a wire or something was failing. Just kinda lost power. I figured out that that was the place on the track that the heat buildup was enough to make it ping. But like I said, it never made a single noise.

Check the float level....it could be sucking a bowl dry. I had the same problem when shifting at 6k. I increased the float level and the problem went away. I am running 74 front and 84 rear and still have too lean of a mixture.

I agree that it could be the fuel bowl level and maybe the jets. I would also check the fuel pump and or filter. I have GT40X heads with an E303 cam and a 750 Speed Demon carb. My jets are 75/82. I have never tested air/fuel ratio but that seems to be the combo it likes for the 1/4 mile.