The shop is pretty well insulated, R21 walls R38 ceiling. In the top picture you can see the natural gas meter for the house, all I had to do was tee in and dig a trench over to the shop. The heater is a Modine Hot Dawg. At 75K btu it is probable a bit of overkill. Heater placement is not critical from what I can tell, it was most space efficient for me to put it in the corner. I will add some ceiling fans before next winter. The heater was very easy to install and can vent through the sidewall, just check on eve clearance to avoid condensation problems.
I have enough cars to fill it. The TR4 is in the attached garage, there is 77 Lancia Beta under a cover outside, a 39 Ford Standard off site and a 41 B John Deere at a friends. I am sure the shop will "shrink" when I start restoring the Ford late this year.
I will need to move things around to paint the floor as soon as the weather becomes consistently warm. The paint guys tell me that heating the shop is not enough, it needs to be warm outside as well. With the expense of the paint, I did not want to risk a mistake.