I went to a radiator repair show here in town and they fixed mine for 100.00 bucks. i was pissed off when i found out all they did was hit it with some paint stripper then put a high temp epoxy on it and spray painted it to match.
Yes it worked for many more years without any problems, but i felt i got ripped off, i could have done it for 5 bucks. Just get some jb weld or find a high temp epoxy and patch it up, youll be fine, dont use the sealer it will screw up a perfectly good race engine.