Recently I tried to get mine boiled out and apparently the EPA got all excited about the acids in the hot tanks and no one does that anymore.
I did have some radiator shops in TX that would make radiators, but I never got a tour of the shop and suspect they were running the product across the border.
To that end, I would try capping your radiator then with it upside down, fill with cleaner and try rodding (sticking welding wire through the tubes) to clean it out. Be gentle as you don't want to go through the radiator. Be sure to use distilled water, not tap water.
And good luck!
Andrew