Definately strip them down. They are usually fairly easy to strip. After copper plating, use a masking agent on the piston bores, bleeder and banjo bolt threads. to prevent plating build up. Tripple plating builds a fairly thick layer. I zinc plate calipers all the time with no need to mask.
A modeling masking agent like testors masksol works perfectly for masking. I use it all the time. Have a look in your local hobby shop where they sell plastic models and paints.
Stripping is a good idea anyway.... nothing like freshly greased seals to bring brakes back to working as they should
Use a proper brake rubber components grease when putting them back together.
Cheers
Mark