Thanks for all the replies. I will not running the Airtemp compressor, Engine will be a 472 w/solid cam and the Mopar dp intake, About what the crate motor from Mopar was. Nothing radical. Car has the original 26" rad probably needs re-cored anyway. It's not a fresh air car. The 340 in the car is tired Iv'e got everything besides heads and crank from having a complete 426H, But it's the only A/C hobby car I got and would stay a 340 if butchery was involved. FWIW a friend bought a spirit of 76 d-150 new, 318 auto with air, within 2 wks of purchase it rolled out of his garage with a 68 426 and still with air.