I believe you want closer to 12cfm @90psi in the 'painters' world.
If you only do a fender at a time you might squeak by with your proposed set up but for anything more than a few minutes your compressor is gonna run a lot and that makes heat and heat in your airlines makes water and water firetucks (sans the "iretr") your paint job every time... Water and oil vapor in the lines needs to be filtered out in any case.
