Use somthing accurate to measure the ID at the top. Accepting your statement that the quill stem is 1", I infer that the steerer is 1-1/8" at the top, (based on a typical 1/16" wall thickness). That was a somewhat common size as threaded headsets began to give way to threadless systems.
Note also that there were a number of "tapered" steerers which were more like "bulged" or "stepped" and were larger at the crown than the top. These were fairly common BITD, though I'm a bit surprised to see a threaded one (if that's what you have).
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.