If it was over 100,000 I would say go back to zero.

But, at 76,000 leave it.

Your entire resto will be documented at that point anyway. To me, a car with less than 100,000 original miles carries alot of weight, more so than "numbers matching drivetrain". At 76k many of the pieces you take off should be able to be cleaned/polished/painted back up and put back on which (to me) preserves the originality. When I'm buying cars I look for originality and straightness of the body, I could care less if the engine's been swapped 20 times.