The goal is to have the bolt close snugly on the go gauge once the barrel is torqued in place. You want to feel the gauge as you close the bolt without having to force the handle down. I normally torque at 90 ft-lbs and that means that I wont feel the gauge when I close the bolt on a hand tight action.
do this test, with the action hand tight on the barrel and no headspace qauge in, close the bolt and see how much movement it has forward and back, there could be 0.010 or even a bit more depending on the action. Now put the go gauge in the chamber and if you are chambered at the right depth, this back and forth movement should have been reduced to 0.001" to 0.002"
The shoulder area always looks rougher than the sides when you look down the chamber, but it doesn't mean that it needs polishing. I would never go and retouch or polish the shoulder unless I had fired the rifle and found that there was a problem with the chamber. If you had the right pilot and the rest of the chamber is fine then the shoulder should be good and your job`s done.
Thanks pre 64, I believe my job is done I'll assemble tomorrow, lord willing and see how it came out.