Interesting combo. I imagine that the 500T bridge is quite a lot more powerful than the Jazz neck?
If you're definitely going with PK or MM in the bridge & can live with the existing power inbalance between the bridge & neck then I'd say Holy Diver neck.
You'll get the same brightness & a very clean, clear sound that lends itself to sparkly clean tones, but the HD neck does it a lot better than the Jazz IMHO :)
Of course, there are several other things to consider here: what woods your strat is made of, what sounds you want to achieve etc, but whether the PK or MM are the best choice for you or not, they're still a huge improvement over the 500T :)