Nowadays the fun police and poor parenting have taken risk and inventiveness away from children.

I'm also interested to see how this worked out.   In my early teens, around the time this gun was manufactured, a good friend had a meteor and it was the first air gun I regularly used.  I have fond memories of scaring the local sparrow population with it. I recently purchased an early super meteor of a similar age from Ron Young.    Mine is a bit rough looking but having been serviced by Ron does shoot smoothly.  I ran it over my crony this afternoon and it is putting out 8.5 fpe at the muzzle  with 36 fps between the highest to lowest speed over 10 shots.

I'm looking forward to some fine weather so I can see if I can shoot my one any better than the one my friend had!  

Don't overthink the barrel straightening. It doesn't need to be surgically straight from end to end.

It only needs to have the muzzle approximately where the sights / scope rail align usefully.

Take advantage of a small bend near the breech producing a large deflection at the muzzle.

It almost certainly bent at the breech end to begin with, due to the physics.

So you will likely be reversing the bend where it occurred if you only clamp the breech end

and pull it back down.

Im thinking its the whole breech block and barrel thats pointing upwards... I dont think the barrel is bent.. 

I would probably try shimming the scope rings. if you have open sights they are usually on the breech block so doesnt matter if its not straight as front and rear are both on the same angled line... 

I had a BSA lightning that had an upwards barrel - shimmed front mount with some milk bottle strips and I could get it zeroed ok at 25 yards

To me it doesn't look look like the barrel itself is bent, rather poor matching of the breech mating faces allowing the barrel to rise above the cylinder centreline.

Not easy to fix, and having rebuilt a Meteor roughly 12months ago, they're junk and not worth wasting time on (IMHO).  The engineering is appallingly bad.