A barrel for the Crosman 1760 can be machined to work in a 760. I bought one from Mountain Air custom airguns several years ago for my customized 760. I read somewhere that 1760 barrels are getting harder to come by from Crosman, but a .177 Discovery barrel is basically the same thing and it's even notched like a 760 barrel for the rear sight.
My 760 is one of the newer ones with the 5 round pellet magazine (or clip as they call it). Makes it a lot easier to load with a scope on the gun.
On the other hand....
You might try looking for an older Crosman 66. I picked up one from the 80's for $20 at a flea market a couple of years ago (metal receiver) and it was almost like new. 66's had a rifled barrel since they first came out until just recently. Mine's deadly accurate with Destroyer pellets. Little longer length of pull too.
I plink, therefore I am.