Hope you have some heat in that little garage. My fingers become useless once the cold sets in to the bone.
Is your engine all together and running?
Or are you going to clean it before you put it back together?

If it's together and running, a scraper, wire brush, lots of rags and simple Green will clean it up, but not as good as a pressure wash and that isn't as good as a bath in solvent. You'll need to transport some water. Several 5 gal buckets full.
YOu could boil some water in pots on a kerosene heater, i do it all the time in my shop. Hot water has many uses, as well as putting alittle more heat in the air.

If it's apart I'd take it to a car wash (if they work in the cold up there) or find a machine shop that will dunk it. Do it right if it's apart.
Good luck.