Nice build sir. Just wait until you have your spray foam and batting in. Makes it a much more comfortable space. Are you spraying the entire building or just the underside of the roof?
I built a 48x64 shop with 14' walls. Sealcoated the walls with 1" of sprayfoam and finished filling the wall cavities with R19 batting. I put a steel ceiling in mine and blew R49 of fiberglass insulation up there. We had a party with 40 people in there last week and it started a 68 degrees and ended up at 72 which is the highest I've seen it. It's been over 90 degrees here in Ohio off and on over the last few weeks also.
It's a spendy initial investment, but sprayfoam is the way to go in my opinion if you plan on spending any amount of time in the shop in the hottest and coldest times of year. I finally talked my brother into spray his 30x40 and he now wonders why he waited so long.
Again, nice shop!