4 piston, small bolt pattern caliper rebuild

Rebuilt the calipers in my 65 Barracuda (not original to the car). Hooked everything up and applied the brakes. Fluid leaked from some or most or all of the brake line fittings (been a while, can't remember how many of them leaked). Took me a while to figure out what the deal was, but turns out the brass (?) compression fittings at the bottom of the threaded brake line holes in the calipers were buggered up from the calipers having been rebuilt who knows how many times in the last fifty years. Took a look online for replacement fittings, found nothing. So I just ordered a pair of rebuilt calipers from Rock Auto. They are fine, but now I have a pair of freshly-built calipers left over that I can't use without replacing the compression fittings.

Are the fittings available? Can't imagine they wouldn't be (the rebuilt calipers I bought appear to have new fittings), but I've been unable to find them.

If they are available, is there a trick to removing/installing them?