Radiator upgrade for engine switch?

[DeltaMustang65]

What's the name of your shop? Do they have a website? I'm willing to bet the radiators you're talking about are the aluminum cross flow variety found in 5.0s. I see them in 60's Mustangs around here from time to time, but I don't see them as necessary. I've heard that they like to crack and split in places, too, but that may just be rumor.

If you're in Canada, you should be fine with a 4 or even 3 row copper/brass radiator that would have come stock on a 289 car. The only reason I decided to buy the 4 row version was because I live in California and it gets up to 110 F in the summer. My 289 is mostly stock, probably making about 220 hp. Maybe that'll help you as a reference point.