The Casino does not have a stop bar tail piece. I was hoping that I could get away with re-using some of the existing holes, but by my reckoning, both sets of holes are off by nearly a quarter inch to the bass side!
And that can make putting a Bigsby on a guitar a finicky, frustrating job. Use your nut, neck, and bridge to determine your center line, and try and get your strings over your pole pieces, in a straight line with your nut and bridge Before you drill the holes in the top of your epi, see if the hinge on the Bigby is center in relation with the main plate that lays on top of your guitar: The important thing is how the strings line up with the neck.
You can fill holes with small diameter dowel rods and glue to do a cleaner job than with toothpicks. Keep in mind -- you will need to run a new ground wire to the Bigsby. Worst thing that can happen is Center of the guitar means nothing, and pickups all casino in cambodia don't quite line up with the strings.
Make sure your ground wire is in good contact with the hinge plate. Make sure that wire is in direct contact with the metal surface of the Bigsby -- you will probably have to remove a felt pad in that spot -- and then reinstall it over the mounting screw so that it sits between the wood surface and the ground wire. Remove the bridge pickup -- you will see a ground wire attached to it that ground connects to one of the threaded shafts for the stop-bar stud bolt.
Make the bigsby line up the strings on the fingerboard here you want them, and then make sure the bridge is centered under the strings. It seems like many people just go ahead and drill through these tops with no center block. If the ground wire is between the wood top and the felt pad, you tailpiece and strings will not be grounded.
Here is a picture of the model: The other question is a matter of you like the looks of it.
I'm leaning toward just going for it. You might prefer to have the strings slightly more to one side of the neck. The Sorrento had a stock trapeze tailpiece, and at some point it got tricked out with a Frequensator, so it already has a bunch of extra holes drilled in the bottom.
Sometimes the Bigby doesn't hang straight off the hinge plate and you have to shim the hinge plate slightly. Get some small maple dowels. Does it just not matter as much for a trapeze style tailpiece? It will add a couple of ounces to the guitar's weight oz.? If you ever need to plug a bad tailpiece drilling, I suggest you head to your nearest tiki bar and order up the rum drink of your choice!
If you decide to install a B7 by itself -- you should be fine with mounting screws drilled through the top without a center block.