Hi John,
If you know there is a key change in an instrumental what I tend to do is as far as possible is make sure the fingering pattern is going to be the same. What I mean is instead of learning a new note pattern for the key change just shift the same pattern you played in the lower key up to the new key. The worst one for this that I've done is the Waffles track 633 Squadron, it was a nightmare and a lot of changes with open strings. I eliminated the open strings and just kept moving the same pattern around. It really helps as you dont have to remember half as many notes.
Tony