Barbara Gordon is an interesting one, no doubt. It seems obvious that the whole "getting crippled by the Joker" thing doesn't really fit into the spirit of the pre-Crisis metaverse, but, as noted, Barbara was semi-retired heading into Crisis (although I personally though that a LOT of her whining during the ACTUAL Crisis came out of left field). I kind of like the idea of her hanging up the cowl and continuing her political career (she was a congresswoman pre-Crisis, after all), a crusader for high tech within the halls of Congress ("The Oracle of the Potomac," if you will).
Booster Gold, as others have commented, despite being an explicit post-Crisis creation, has some remarkably pre-Crisis notes in his origin. I mean, he was a janitor in the flipping Space Museum, for goodness sakes - it doesn't get more Silver Age-y than that. So I could see an argument for a version of him cropping up, although it wouldn't be my preference.