This may sound dumb, but before I had access to proper tools I cut some shotgun barrels with a pipe cutter. Of course, it won't work with a ribbed barrel. I didn't cut all the way through. I just scored the barrel and finished the cut with a hacksaw. It came out square. and I just finished the muzzle with a file.
The main drawback it that the wheel of the cutter leaves a ring in the finish near the muzzle.
You can get pretty close to TDC with the help of a friend. Put a piece of masking tape on the area where you want the bead. While you sight down the barrel of your UNLOADED gun, have a friend hold a pin vertically in the spot you want the bead. Have him move it until it looks right to you. Have him mark that spot. You will be at least as close as most factory barrels.