I'd go for routing out the top channel as preference, if you rout too deep and screw up, you won't see it, and the glass will have room to move up into.
Filing the bottom part and screwing up, means you will see that mistake everytime you play the machine.
I'd (probably) pay $300 for the REAL DEAL, and $50 for repro.
Why some people still insist on charging 'REAL DEAL' prices on repro items is beyond me. greed greed greed.
Take a look at repro cabinet decals and translites, what a joke !!
I still think advertising the size of the glass may have helped, obviously they know to make the sale 1st, then put it back on the customer to fix it up themselves.
If they stated the sizes, i don't think they'd make many sales.....
MM.