The headtube is reamed to spec 33.9mm inside diameter. It's done the same way I did the Swing bike only that was to a 30.1mm Inside diameter because the frame use a fork with a 1" steerer and not 1-1/8" like this frame.
This frame is going to have a 1-1/8" fork steerer. Remember I used a 1-3/8" (34.9mm) O.D. tube with .035" (.9mm) thickness, resulting in a tube with 33.147mm inside diameter that needs to be 33.9mm. So I had to increase the inside diameter by .75mm or take .375mm off the wall.
. . . now the bottom bracket area is cleaned up
Now on the the Seat stays.