Why don't you measure the height of the bridge screws you have on the bridge now and see how much longer you need them to be? Try the link below, they sell Gibson diameter studs and wheels with studs up to 1 1/16th inches long.
Link:
http://www.guitarpartsresource.com/gbridge_studs.htm
Roller saddles are a pain and Walter doesn't care for them for all the right reasons, but you've got a lot of break-over angle, which means your strings have a lot of down-force on the bridge, so a roller bridge might sound fine. I used a Schaller roller bridge on a bluesbird and it worked okay. Re the true-arc bridges, I bet they make some of those serpentune models out of material besides stainless steel, too.
Good luck!
OK, I ordered the 1 1/16" SAE Nickel studs and thumbwheels. (BP-2394-001).
Received them today and installed them on the guitar. They were actually a little too long, but I took care of that with my heavy-duty wire-cutters and a small file! Fits perfectly!!! And works just fine. Solid.
And I put a little cello rosin under the bridge to keep it from sliding around.
So, I figured since I'm going to keep this saddle for a little while, I might as well experiment a little, so I strung it up with D'Addario Chrome flats 11-50. (22 Wound G). The intonation on the G is a little flat. I had read somewhere that the Bigsby saddle was intonated for a plain G, so it wasn't unexpected...but its only a tiny bit flat at the octave (better than being sharp!). I had a wound 18 on it with the last set and it was fine actually. I can live with it. All the others are spot-on!
The feel and tone of the flatwounds are going to take a bit of getting used to. I kinda like them and kinda don't! I will reserve judgement until this weekend's gig. I want to see what they sound like with the whole band! They are warmer and less "Kerrang-y", and they kill on the Duane Eddy stuff! They DO seem to go well with the DeArmonds! And you can slide up and down the fretboard effortlessly and quietly...but I'm kinda used to that round-wound friction and feel. And bite. Again...reserving judgement til the gig.
I did NOT file the bottom of the Bigsby saddle flat...just to keep experimenting. With the longer posts it's a lot more stable.
I think I'm going to order a tunomatic. ABR-1. I just like the option of being able to intonate each string individually. And I never had a problem on my other Bigsby-equipped guitars with the tunomatics. I want to be able to experiment with different string types and gauges, and that's the main reason I don't pin the bridge!
Thanks for all the replies, insights and opinions, and sharing your experiences!