Air compressor sale

For 90% of my needs my current compressor is overkill. But when I get to running my sandblasting cabinet it does struggle a bit. Once it kicks on it doesn't stop until a few minutes after I stop blasting.
While blasting it gets down to 90 Psi and stays at 90 til I stop blasting. It's rated at 17.some cfm at 175 psi (might as well round it off to say 18) and (I forget which, either 21 or 24 cfm rated at 90psi)

I have an 80 gallon tank with my compressor, my cousin has a bare tank in his garage that I've been told before that I can have, since he has realized that he will never get around to building the compressor he wanted to back when he got it) I believe his is a 120 Gallon tank. I have been seriously considering it, and plumbing it into mine so that would give me 200 gallons of air capacity. I need to pour a pad and build an "outhouse" size shed behind the garage for it and my existing compressor before I can do it.
Back when I built my garage, my compressor was housed in my 10x12 shed which is on the opposite side of the house from the only spot on my lot where the building inspector would allow me to build my 30x36 garage, I'd had it plumbed into the attached garage back then, I only had to run 15' of conduit from my box to the shed and 10" of air pipe back thru the wall to have air in that garage without hearing it bang as I worked. My 1st workaround was 125' of air hose from the compressor to the new garage whenever I needed air out there. I eventually moved the compressor out to the new garage, and I now have to listen to it bang away any time im out there working..... So I want to build an add on outside "closet" right behind the garage to move the compressor into.