I will say this that I had my 850 Holley DP jetted for the track and dialed in pretty good. But I felt it was a tad fat at part throttle when cruising and it is an older model as the only jets in are the main jets. Everything else has to be drilled and or tapped for jets. I was going to modify the idle restriction and transfer slot sizes but I decided to drop the primary jets a bit first and then open up my primary power valve channels some to make up for the less fuel at full throttle.

And I only had to drill just the P/V channels. I dropped my main primary jets a few sizes and opened up the P/V channels the same amount as I measured the sizes. And it has worked great as it cleaned up my part throttle very well and it seems to still pull as hard. But I have not been back to the track to verify my trap mph although the car feels as strong when wide open. I did not want to change it much because it was dialed in great at the track so I went with the simple jet change and drill the P/V channels first which has worked good for me. One thing I found is if a carb has been messed with and I don't know who has done what to it I like to go back to stock jetting and then work from that. Good luck with it. Ron