I have two AD lite preheat ballasts with rotting cloth wires. And the tar is making it a huge pain in the butt to repair them. What is the recommended temp to heat them up to remove tar while not damaging components?

Frankly im not sure, but i think the reccomended temp is when it starts to melt

Just watch out for those Tar fumes, dont wanna end up like Ralph Wiggum!

  About 350 F  is the starting point to melt the tar.  Best use a high wattage incandescent and let tar drip out on it own
  Once u expose enough tar.  At that  much trouble u might as well  remove the old pcb cap. And extend the wires externally
To remote mount the cap.   

    Ive been making home made preheat ballast to restore lights
 Out of rapid start  ballast.  And using magnet wire from dishwashers.  That been my latest hobby of mind is restorimg
 Old  preheat ballast. 

What are the capacitor values usually? Also is the value critical? Obviously the voltage should remain the same or higher but does the MFD rating matter?