I am in the process of swapping on 4-pot front calipers. I noticed that there is a flare fitting built in to the caliper, but mine looks like it's pitted. Is there any way to fix this?

 

As long as the pitting is somewhat minor and is in the threads and not in the seat there's a chance that it will be ok. You may want to tighten the line in the caliper and see if it has play. If there's play when it's tight, the caliper is no good as it will not seal properly.