[VFRhugh]

Follow up:
Pulled the radiator and took it to the only radiator shop in town. The owner (Randy) told me when I called he doubted it would need rodding out because the tubes are big in a model A. This shop has been in business a long time. Randy has a rig to really put some flow through. After a couple of back flush cycles it was flowing great. It was just rust flakes laying on the top of the tubes. I also took a radiator that was on a chassis I bought. This rad is considerably heavier with larger tubes. Randy said it looks like an original to him. It also flowed great. The whole thing probably took 30 minutes. Randy wouldn't take any money.
This morning I compared the two radiators by running them back to back. The lighter radiator has more smaller tubes & held 165 deg. The heavy radiator ran a little hotter on my APCO gauge maybe 170. My test route included about 5 miles at 55 in overdrive. This is a totally stock engine. My project engine has a 6 to 1 head and IB330 cam. Logic says it will generate more heat so I'm thinking of staying with the lighted radiator. Photo is what I'm calling 170.