So the original radiator should have been a 22". With all the other answers, you probably want as big of a 22" radiator you can get in there just like J par said. I don't see any need to go custom and try to fit a 26" or crossflow unit in there. An original 3 row copper/brass unit may be fine but why not get something with some extra capacity just in case this motor may run a little hot and just to make you comfortable when you get stuck in traffic on a hot Missouri summer day. :) I'd recommend a minimum dual 1" and consider a dual 1 1/4" tube aluminum rad. if you have enough clearance for your water pump pulley. Griffin, Be Cool, Cold Case, Dewitt, ECP, American Eagle division of Champion are all good brands. Of course we hope you give us a good look before you decide. :)
