Another APS-2 in the mid would do it.
As far as what bridge pickup you want, do you want a humbucker or a single coil?
If you want a single, Another APS-2 would work well. I have a very similar set to this in my MIJ 62 RI strat and I love the sounds I get from it.
As far as humbuckers go, an APH would be great, or for more output, a Custom Custom.