Install a good cast iron mop sink with large drain boards on each side. Make the faucet like those found in laboratories that allow enough room under it for big objects.

Install a toilet so if needed you could convert the place to a 'granny flat'.

Install lots of electrical plugs. Don't forget a couple 240 volt for welder, etc. Instead of buying a lot of expensive welding cable so that you can weld outside, but a 50' piece of 3 core 6 or 8 gauge so that you can roll your machine to the job. Much cheaper.

Make a heavy duty steel welding table where you can mount a 6" vice. I made one out of 2 pieces of 2'x3'x1" plate welded together and 4" dia. sch. 80 legs. Nothings moves it.

While you are pouring cement make a 20'x30' slab attached to the shop for a pole barn. Connect it with an 8' wide roll up door.

Install lots, like 8 fixtures, of lights.