I have a non pitbull guitar without the longer bari neck with a roller bridge and imitation bigsby and it works fine. Yours can work as is with one slight adjustment but you need to make a measurement before changing anything.
Either remove the nut or put a capo on so the strings sit on the first fret. This just makes it like when it is in playing situation and makes the next part more life like. Remove the 2 adjustment screws from under the bridge and let the bridge rest on the inserts or the body. If the string height is right or the strings are resting on the neck then all is needed is to recess the inserts into the body by recessing where the head touches the body by using a Forstner bit or carving it out by hand.
Use a piece of dowel you used before to plug the hole and this will give the bit a centre to locate so it doesn't wander while drilling. You can adjust the diameter of the dowel by putting it in a drill and using sand paper or a file to reduce the diameter so it fits in the hole. The depth will be the thickness of the insert head above the body and the thickness of the screw part that the bridge sits on, maybe around the 5mm mark. If need be you could remove a little bit of material off the bottom of the bridge to allow it to go even lower. Just use a piece of sandpaper or wet and dry and rub the bottom to allow it to sit lower.
If this works then it is the simplest solution and if it needs a little bit extra you can use the shim to give you what you need.