standard to automatic

[Geos 72]

Hello to everyone out there, I have a 72 Chevy C10 Cheyenne that was an originally a 6 cyl. with a manual three speed tranny with the shifter on the column. Before I bought it who ever had it put a 350 in it (bored out to 30 over) and put the shifter on the floor. At first I didn't mind the shifting but now I'd like to switch it over to automatic. I realize I have to get an automatic tranny, an automatic steering column w/ the linkage, transmission lines and probably a different radiator since the one that's in it doesn't have any tranny line hook ups. I thought of using a transmission cooler but two transmission shops that I called told me they would not recommend using a cooler, they said the radiator would be much better. Has anyone out there ever done this? Am I going to be sorry I even tried to do this? The truck is in pretty nice shape but it's no show piece. I sure would appreciate any advice. Thanks, George