UPDATE: Nothing like direct observation! So, I dragged the bike out from the murky corner of the basement and pulled the bar/stem, and dropped the fork out and tapped out the lower race. My digital micrometer is accurate to .01mm, you can guess the user somewhat less so. Outside diameter if head tube is very close to 31.75mm (31.8 to 31.82 actual, but there's paint) and the inside diameter is as close to 30mm as I can get a clear reading. Do y'all think it's safe to procure an English or Italian fork, as long as steer length, offset, and axle-to-crown make sense?

Never did before , but that was the mid-70's and I was an immortal teenager. If I get a road fork, fine, if I get a track fork and one of those $$$ up-through-the-steer adapters might fit, that's fine too.

By the way, When I first got the bike running I was out on it, and decided to cut through the campus of the University of Maryland campus on a weekday afternoon. On a long grade running between buildings I went to slow down and I clearly had not tightened the sprocket's lockring enough, it backed off and the sprocket too. No way to stop, I simply yelled GANGWAY and students scattered in both directions, no one hurt. Not sure how I made it home, at least it was uphill the whole way which must have helped. Well, maybe I do need a brake...