My 66 Pre-Xflow had similar issues. Before I could investigate, I had replaced the Pre-Xflow with a Cosworth BDR. Part of my swap was a new alloy rad. and an electric fan.
Exactly the same overheating issues. I did install a MMC scoop and honestly it works!
Perry, try Morgan Spares in the US for price comparison on the scoop and Dave Bean Engineering for all Ford related stuff.
Since the problem went away, I never tried to seal the rad against the cowl...using scrap foam or whatever.
As far as the fan goes, try Advanced Auto. I got a really nice kit that I used on a GT-6. I didnt have to spend much on it.
