Its not even hot here yet!!! /forums/images/icons/smile.gif I'm in the same boat as you, I've got to get better cooling for my 65. Of course it'll be after unpacking, putting in a patio, landscaping the backyard . . .
Stay away from a flex fan Please, your hands are begging you not to get one. Some people like them I don't. They make a lot of noise. If you are working any where in the front of you motor wear leather gloves. Just bumping the edge will cut you. I have the scars to prove it. I took mine off got sick of the noise and running out of bandaids!
As long as the clutch and fan are rated for the rpm's you'll be running the engine to, I'd recommend a clutch fan for overall performance and noise.
The caveat is, if they're on a spacer, that you make darned sure everything is concentric and running true....that big old clutch hanging out there, spinning a ton of rpm, can make life for the water pump bearing miserable, if everything isn't flying in formation, so to speak...*G*
OK, I get the hint - a clutch fan may be the way to go. See, the deal is that I don't want to spend big $$ on a bigger electric fan, higher amp alternator, and wire a new relay circuit when a big fan driven fron the belts the old fasioned way works OK. As for RPM, my Boss does fine with it's fan - I'm amazed at how cool it runs (no A/C /forums/images/icons/wink.gif). So with the clutch fan at least most of the mass is in the middle. All this is rationalization, Pat, I hear what you are saying! But even a Black Magic fan @ 2800 CFM is not adaquate for my 300+ horsepower plus A/C and that extra 25A current draw is not coming out of my stock alternator, if you know what I mean!
Funny thing - I have a repop 69 fan shroud that is supposed to fit on the Boss 28" radiator and it will fit and align to my Ron Davis Aluminum radiator in the SVO and looks like it will line up with a fan on the water pulley - so I think I will go lift the big fan out of the Lincoln in the junkyard for a few $$ and give it a try!