If you are installing a Bigsby, you can use any Bigsby compatible bridge you want (since string spacing holes won't matter). Fill the screw holes with dowel rods and drill new holes for whatever bridge you choose.
Looking for opinions. I have 3 Les Paul type guitars, 2 Traditionals and a Studio with an ebony board.
Through a series of deals and trades, I have 4 sets of Humbuckers ready to drop in: OX4 low wind A4s/ OX4 Hot Duane A5/ Duncan Slash A2/ Duncan Distortion Ceramic.
Current pickups are Duncan...
Has your friend tried 9s? Going from 10s to 8s seems pretty drastic to me and might create more of a challenge in adjusting his playing than he expects. 9s might be easier to achieve the desired relief too.