air compressor size????

You need to take your biggest tool, determine the air usage, and add some "fudge factor."

Tank gallons has NOTHING to do with an air compressor capacity. All a huge tank does is to allow you a few more seconds before kick in, and you get to sit there a lot longer to wait for it to pump back up

Take published compressor cfm figures with a "grain of salt."

You want cfm specifically rated at 90 psi.

cfm listed at say, 40 psi makes it sound "bigger" and ratings at scfm (atmospheric inlet pressure) makes one sound bigger YET

But even ratings at 90 much be viewed with a raised eyebrow. Consider "who" is claiming them. If it's ANY Chineseo outfit, be suspicious

And don't buy a direct drive anything, nor oil less. If possible, you want a cast iron pump, belt drive.