Is the new Umarex Ruger 10/22 CO2 Air Rifle .177 your answer?
https://www.pyramydair.com/s/m/Ruger_10 ... e_177/4805Would probably be A LOT cheaper than finding a machinist or gunsmith to fabricate the upper receiver for you in metal. If you wanted to stay with any airgun and did not just want to go with a real 1022.
But for me, the Crosman 1077 is just fine. I upgraded to a wood stock, and bought spare clips and magazines so I don't need to stop and reload the clips in the middle of shooting. Now I shoot until I run out of air. Which is around 50 shots.
I had to check my 1077 to actually see what you are talking about. Yes the receiver is plastic, but it never really bothered me.
But you might as well put the question out there, but I doubt you will get a response from someone that has done it.
Airgun Warriors Forum has a metal shop section. Did you try it?
Another option would be to install a wood stock & put a metal scope on it. That might be another less expensive way to cover up the plastic receiver.
Anyway good luck on your quest. Please advise if you find an answer. Some of us might be interested in the modification.