So I am thinking portable, powerful enough to keep the spray flowing smoothly, gas powered to work a far distance from electricity? You may want to start with your paint sprayer, how much air air does it need a minute, to keep spraying smoothly. This is the beginning, compressor has to provide enough air to power the sprayer, to do a good paint job.
If you have not used a sprayer recently, buy a new, cheap one. Sprayers have improved AMAZINGLY in the last few years. We got a cheap one from TSC to paint the old spreader we bought. Husband said it was very easy to use, light to hold, things went fast. Much better, easier to use than his old, expensive sprayer, ”‹”‹”‹”‹”‹ for a fraction of the cost. Read the paperwork in the sprayer kit to know your air requirements.
Then list your other requirements for the sprayer. Now you have a shopping list the new compressor has to meet to be useful.
Lastly, get a VERY GOOD respirator mask to use during painting. Buy the extra filters to go with it and goggles. Don’t go cheap in this area of protection. Sprayed paint particles in the air are dangerous to your health. Breathing them in will coat the inside of lungs causing damage. Air moving outside can change direction fast, so you get blowback paint on you to breathe. Not worth your health to skip wearing good protection. Those cheap paper masks won’t protect your lungs, spray droplets are smaller than the paper openings. .