SHULTZIE- You missed your chance at the best heating method when the concrete was poured. Hot water floor heat!
A Big Time Farmer a couple hundred miles south and west of you that I have complete confidence in his opinion has two hanging radiant tube heaters in his BIG farm shop about twice the size of what your building. He has Big 4 wheel drive tractors, huge combines, sprayers, planters, and a couple semi's to work on, and He's satisfied.
25 years ago when I built my 24x36 shop I should have kicked the contractor to the curb when he wouldn't put in in-floor heat, but there's more to that story. Best thing I did was to finish the inside, 4 inches of insulation in the walls, plus a 3/16" thk foil covered fiberglass barrier, and 6 inches of fiberglass bats in the ceiling. My 100,000 BTU heater only runs maybe an hour, maybe 1-1/2 hour a day to keep it warm if I keep the doors shut, without insulation the heater ran an hour for every 2 hours I was in the shop.
Next shop will be bigger, would put a 12x24 extension on if we were staying here longer, make it 24x48.