I hate to rain on your parade, but that's nowhere close to "very good condition". I hope it didn't cost you too much.
More broadly, you've bought a lot of watches lately, multiples at each interval it seems. It might be better to do thorough research on each individual piece before committing.
I think bezel insert is also a replcement. But 3.5k is certainly a decent price for that Long E GMT.
you can't really tell if a bezel is replaced if the replacement is the original part, I am surprised Rolex gave that assessment as they are normally very conservative on their evaluations of Vintage pieces. I have a 69 GMT. Great price for a vintage GMT. Would love to see more of it. It seems like it has been very polished, if that is the case then the bezel really makes less sense in that condition. I like the Dial but the cracking is unfortunate. Did you get a look at the movement?
Is there a way to prevent the cracked lumes from falling apart?
That cracked lume is cool looking. Rather peculiar for a Rolex of that vintage, i often see the lume more matte and not raised/bubbly.