Just a suggestion...before you go spending a bunch of money on a new radiator you might check out a couple things. First of all, I run an Old Aire system in my 54 truck and have NO overheating problems. However, I did make sure that I had about an inch clearance between the condensor and the radiator, that I sealed the top of the core support shroud so I don't loose any airflow.
In addition, I'm running a flex-a-lite FLX-1615P 15" six blade fan from Summit ($25.00) and only see a 15 degree increase during extended periods of idling. I did add a pusher fan just in case....it's on a manual switch and have used it only a couple of times during heavy traffic backups.
My radiator is a 3 core from LMC....too much (thick) radiator with a condensor in front may impede air flow. If you're running a stock 4 blade fan I'd check out that specific fan as a replacement. On my adaptor plate, early pump 1" snout I had to file out the fan hole to 1".
With summer knocking at the front door you don't want to be worrying about boil-overs or going without your air!
Dave
