If you have the rails rebuilt, it does not matter that they do not match. I have rebuilt sets that came from 3 or 4 different tables, GC1 and GC2 that turned out just fine once they were done.
The rails do matter if there a matched set or not....sure guy's patching up the rails and making the sub-rails the same height of 1-11/16th is not making the rails aline correctly to the table.
The rails are different in thickness....some are wider than others....the apex where the pocket castings meets the front of the rail will have a big gap.
Try lining up the back of the rail and casting flush around the table....then see where your rebuilt cushions set.
That's why they come 6 rails to a set....will the mismatched rails play good....sure has nothing to do with the play of the table if there rebuilt correctly.....but look at the new sub-rail you put on....check the sept down from the formica to the top of the sub-rails....by the corner pocket the step down will have 1/16th and the side pocket will have 1/8..and the feather-strip will stick out like a soar thumb.....chances are the castings will not line up properly to the mismatched set.
The different inserts that hold the casting make no difference....just a way to hold the casting in place.....brunswick changes from the screwed metal on the ends of the rails to inserts....ended in the same result..they both pull out over time.
There's a big difference in recalibrating the rails or recalibrating the sub-rails to fit cushions.
Making a sub-rail height 1- 11/16th with a door planner.....cutting the sub-rail 23.5 degrees..for the cushion nose height of 1-7/16th....gives you a sub-rail that's playable....but from the feather-strip to the back of the rail.....it's not even close to calibrated to fit the tables.
Glen and I go over this all the time.....Glen and I are doing a lot of different things on rails...then we were a year ago. There's still a lot to learn...and things that can be done better...but we're getting better...and finding more ways to fix problems.
If people are going to pay good money for there rail work.....they should get a rail set back that has been calibrated all the way around....not just a sub-rail with wood put on it and new cushions.
Mark Gregory