I had one with the 1 1/4" flues in my '40, although it has a 5.0 engine. I had an electric fan with a thermostat and the fan never ran while moving and would usually idle for a few minutes at a stop light before kicking on. After about 12 years it started leaking. I called Griffin and they suggested Barr's Stop leak. I put the aluminum stop leak in and the leak stopped with just a 7 pound cap but the radiator never cooled as well after that.
I replaced it with a PRC radiator last summer and am happy with it. The Griffin had thicker side panels on it, but that is the only advantage I see with them. I think you can get a radiator that cools just as well from US Radiator, PRC, etc for less money. I'll let you know about the PRC Radiator in another 10-15 years.