You sure like putting thumbprints on my rose-colored glasses... looks like the first AK parts I need to program for the CNC are oversized barrel hardware.
Trust me I have thought out your build in my head more than a few times in the last few years. Not trying to put a damper on your build infact just the oposite. The barrel pin hitting the chamber has held me back. with your threaded barrel reciver you have a good starting point.
I suspect you could sell a few over sized barrrel gas blocks if you gould make them cheap. I need one for my 444???? project. I have considerd doing just that but on a hand cranked mill it would not be cheap if I sold them. you mention having CNC that would change every thing. I would go with a standard size bore but just add more meat around it so builders could bore/drill it to what ever barrel they desired.
if the inside deminsions of a L1A1 gas block would work that would be your easiest route an give you adjustabilty. the hight differance is minimal and it culd be ran as is with some slop or a of set piston head could be made to correct the slight misalignment.
on my varmit build I went to a lot of effort to make a tight fitting bore that hald the piston for around a 1.5" in a effort to be able to make the port smaller.
IMOO sourcing a 50 beowulf would be the first step. If you find a reamer let me know Id be interestd in having a barrel chamberd.