Re: older concrete to SWG
Yes it can be done. I'm not sure why your pool, regardless of age, should be a problem for a salt chlorine generator.
Do you have any leaks? This would be a problem with older pools but then again, any pool, old or new, with a leak, will cause problems.
Is your plumbing PVC or metal (or other)? Metal pipe, be it copper or galvanized pipe, would matter also, depending on the condition of the metal, and if your pool is properly bonded (electrically). Any signs of erosion and stray voltage would be accelerated by the addition of the salt because of greater conductivity in the water.
It's only worth the investment if it fulfills what you're expecting it to do for you. I travel quite a bit and all I want is for the pool to be clean and safe while I'm gone, without my wife or kids having to do anything to it.
Re: older concrete to SWG
I will have to check into the bonding more as I was told last year there was a problem with that as on the hand rail is has discolored beneath the water line.