Starting build, please review my parts

[caver101]

First all, just found this forum. Looks to be a great place with TONS of info.

What I have is a ~14", 3 grove, 6.5 twist, PacNor super match SS barrel blank, JP adjustable gas block, M1S pistol length gas tube, cheap DPMS aluminum FF tube, RRA upper (with M4 feed ramps) with RRA bolt/carrier. Will be used on a SBRed lower and with a AAC Cyclone suppressor. The gas block will have to be turned down to fit under the FF tube (and I want a hole in it so that I can adjust the gas without removing the FF tube). So do yall see any problems with these parts? GAP is going to chamber and install the barrel extension and drill the gas port. But before I send all the parts in I wanted to run it by you fellas.

Questions:
I have read the other post about gas port diameter. So I am under the impression that with the pistol length gas system I will need a 0.085" gas port. Does that sound correct?

Any good/bad things to say about the JP adjustable gas block?

Barrel length, would like to have it about the same as the FF tube length so around an 11"-11.5" barrel. Do you foresee any problems? Maybe any "yaw" with the 220-240gn SMK bullets at 1050fps with that length/twist combination?

Also looking for a 20MOA (or something close to it) scope base to mount a Leupold 4.5-14x50 M1, any leads?