I agree -- use the stock radiator. I have a 351 Cleveland motor with 4v heads custom mounted in my 1960 F100 short box on a Volare/Aspen torsion bar IFS frame convert. I run the stock radiator which I had re-cored many years ago. My Cleve always ran hot though. I considered switching to an aftermarket alumiminum radiator. But instead last summer decided to try a "flow-cooler" aluminum water pump which I ordered from APC -- basically a stock aluminum pump with low rpm "anti-cavitation" flow shield riveted on. But I was pleasantly surprised what a huge improvement it provided at idle. Also I haven't run crankshaft fan for many years (electric). That too was a problem as I could never get an electric fan to pull enough air at low speed or idle to keep my Cleve cool (e.g. fast food drive through on hot summer day). I solved that problem too last year by setting my stock brass radiator back (ample room) about 3 inches from stock posn with longer bolts and pipe spacers then adding both both "push" and "pull" electric fans (both sides) of radiator now have elec. fans. Now I never seem to run much above 180 degrees Fahrenheit no matter what kind of driving I'm doing or how hot outside.

Sources: APC

I once had a 60 Ford F100, the previous owners had put a 302 in it from a comet (64 or 65). I seem to recall that the stock radiator was used, it had a large tank top with flex hose, it worked well. For fan clearance you should consider stock, not to mention stock just looks better!