Nice pick up Peter!
Having a new backglass will make a big difference to the machine, and Gorgar is definitely worth it.
Would be a good idea to use #47 globes behind the backglass - they are not as hot as the #44's and only slightly lees bright (not really noticeable though).
The score displays are pretty close to the glass, but this shouldn't be a problem.
Might be worth trying some of the white defused LED's....I reckon that would have to have the least amount of heat?
Fair point actually... LED's will be almost zero heat.
To keep the backglass looking the same though, use "Warm White" LED's - these give about the same colour as the original globes.