I just built mine out of junk.
I have a old Briggs and Stratton flat head engine powering an air compressor head that I got at a yard sale sitting on a wheelbarrow air compressor tank/frame I bought from the scrap yard, only new parts on it are the belt and the bullwhip unloader.
My gasoline powered air compressor easily out powers my homemade 3hp, 240v electric air compressor.
If you get one that has a 6.5hp Honda engine I'm sure it will make plenty of air.
Roofers that use them usually have 160cc powered ones which about 4hp and the compressor stays unloaded about 80% of the time running 3 roof nailers. I had no problem roofing running 1 roof nailer with my old 120v sub1hp electric air compressor. Had the air pressure going to my nail gun at 55psi and that little air compressor had no trouble keeping up with my buddy laying shingles and me nailing them. It ran maybe 50% of the time.