I have a 1951 F1 that I'll be putting a 351 modified with C6 in this weekend and was hoping someone knew what radiator would fit without too much trouble?

 

Obsolete Ford Parts makes one for your application. 800-654-3247. I going mostly original, but I saw this in their catalog, the "street rod radiator" for a 48-52. PN#21C-8005-SRSPO. They cost $499, that's the only downfall, but it does have an automatic trans cooler built in, and the fit is supposed to be perfect, so I would say it's worth the money.
Gary