Why not kill two birds with one stone? The best method to re-blue a 760 barrel, to me, would be to upgrade to a new rifled barrel to replace the original smooth bore. This can likely be done for about the same price as re-bluing chemicals. That is, unless your 760 happens to be rifled (most weren't).
As far as the receiver halves go, they're a zinc alloy, not aluminum. I've had good results by stripping the old finish with aerosol stripper, (use a wire brush to clean out the logo area), then cleaning thoroughly with acetone, then priming with "self etching" primer, followed by a quality "rattle can" black. Zinc is soft and it's easy to clean up deep scratches and gouges with sandpaper after stripping and before cleaning with acetone. I go a step further and file and sand down the casting flash, and blend the areas where two mold halves make a line.The self-etching primer is intended for aluminum, but it also works well on zinc alloys. You can find it at an auto parts store. Also, your paint job will last a lot longer if you knock down the sharp edges slightly with sandpaper. Sharp edges look awesome on a blued gun, but on a painted casting the paint will quickly start chipping wherever machining has produced a sharp edge.
I can't believe that someone would just throw that beauty away, but people throw away good stuff all the time.Mine are all black as well. (They look to have originally been a gloss black too, though most are pretty worn now.)
That makes me want to start checking out dumpsters/dumps.
The barrel for a crosman MK4- 177 is a direct fit for the 760. Not sure, but, the new 760 pump tube should work, as long as you don't have a self cocker.