I am sure this can be repaired if you take it out and take it to a radiator shop. I believe the end tank will have to be removed. With all that in order and cost, I probably would just get a replacement radiator to drop in.
If you used Genuine GM oil cooler replacement lines, you will most probably be doing that repair again. Genuine GM lines are garbage. They WILL leak at the crimps sooner than you would expect. My company takes the complete old line sets to a hydraulic shop now. They reuse the ends and attach stainless steel braided lines to them. Never have to mess with them again!
Good Luck, James