WHich Chemical can be used for Stripping the Radiator for paint

Methylene Chloride......Likley what will be in the A/C stripper....Spray on gel that washes off with water....

Do you think that the use of this stripper would have any adverse reaction with the copper brass and solder?

A bunch of years ago when I did HVAC we used an alkaline condenser coil cleaner. It was a concentrate that had to be diluted prior to use. This stuff was very corrosive and would eat up the aluminum fins which is what I want to avoid on the Rad. lol