From what I've read while researching the A/C subject, the modern rotary compressors don't take as much power to run as the older compressors did. I have a 0.60 over 59 model 261 in my truck, has a small cam, headers w/dual exhuast, 390 rear and will run 70/75 all day long and not break a swet. So I would have no hesitation about installing A/C If I had the extra $$$.
