Are you having it re-cored? If so make sure he uses a core that has fins/pattern that match the original.
Is he is just taking the tank off, rodding it , flushing it and putting the tank back on? Make sure he doesn't gob up the seams. And take the time to straighten the bent fins.
Do not let him paint it, you paint it with Eastwood's radiator paint and make sure you spray the fins from the bottom, and from the top, back side and front, it usually takes two cans.
The Eastwood paint allows the radiator to do it job better than plain spray paint. Do it all in one session, meaning spray a good coat let dry, spray another etc until you are happy with the results. If you come back the next day and try to spray more coats it may lift.