All I have been able to find is talk about removing all of the head bolts.
I would like to add a bracket to the top of the head. This would require of removing just one of the head bolts. Will I really mess things up by doing this? Do I need to torque it down a little more?
I am trying to avoid a warped head.
I don't think you will have a problem. Tighten it to the original torque if you know what it was, otherwise 50 ft/lb.
Remove on a cold engine, don't torque more as now you will have less threads holding with a bracket under it, I replace the 2 bolts on the 26/27 coil box with a longer one when working on that year T.
I'm chicken, I'd only go 45 ft/lbs. If you get a longer bolt, try it in place without the bracket to see that it doesn't bottom out before it would tighten against the bracket You might even run a bottoming tap down the hole, if you can get a long enough tap.
I hope it won't mess it up, because I removed one head bolt to attach my new horn on my 1924 cut-off touring car (now a pickup). After I mounted the horn, I re-torqued the one bolt to 55 ft-lbs in a few steps (30, 45, then 55). While I had the torque wrench out, I checked all of the other bolts, they were fine. Seems to be holding fine with no harm done.
You'll be fine.
Absolutely no problem whatsoever. Just put it back & torque to 50 - 55 ft.-lbs. and you're done.
Never used a tension wrench on a T yet, no striped threads, broken bolts or leaks, just the way Henry did it!