Tony, almost sounds like it would be a shame to pass on the GN without getting a few really nice timeslips and photos before she goes, you have some nice equipment on her and should be a fantastic performer, what are the chances your car is suffering from inadaquate valve springs? there have been many people struggle with having all sorts of good pieces combined that never ran as they should have, all due to weak springs.
Would be a very cool thing if you could hook up with a few TB brothers for a weekend of precision adjusting and tuning then a planned outing at a dragstrip for some video and timed runs, might be able to make the decision easier(either way), wheels up with a "tenner"-she stays, spinning slicks and misfires-she goes.
Best of luck buddy, either way, you've taken great care of her, kudo's.
Kevin.