Front Brake Caliper - signs of wear - can it be repaired

Hi All - well with the help of chacal and hogfiddles I have my 82 xj750 seca back on the road, well it's running
put it that way. After the second test ride I noticed it was sluggish to get going and sounds from the front brakes.
I found that the front brake pads were not releasing from the disc. So after reading some threads and
watching some videos I dove in to pull them apart.
I have them both pulled apart and cleaned. However, I found pitting on one of the pins.
The big issue is inside the one of the pins bore holes is a cavity. It looks like it rusted to the
pin and over time created a cavity. See pics.

Questions:
Can I reuse the pin that has pitting? Should I sand/grind it smooth?

Caliper body that has the cavity in the pin bore hole - can the cavity be filled and reused?
JB Weld? The pin that goes into that hole is not pitted and in good shape.

I apologize if this isn't the correct place to post this. I did check for other threads and didn't find
one that had a similar issue.

Any help/suggestions would be greatly appreciated!
Thanks - Motown

 

Oh and 3rd question:
I'd like to repaint the calipers black like original. I have high heat VHT caliper paint. I was also going to
use a high temp clear coat when done. Any other suggestions for paint?