Looks like you've got several possible solutions already but if you're willing to make a trip out of it then there's a lot to be said for Attitude Aviation in Livermore, CA. The instruction is excellent, they have a whole bunch of planes (you can fly a Waco when you get fed up with the Pitts), and when you're not flying, you're just a short train ride from San Francsico.
Don't underestimate the Pitts. It is a seriously hard machine to land (but an absolute delight to fly). I can't imagine doing a tailwheel conversion directly to the Pitts. It seemed hard enough in the Citabria (which is an absolute pussy cat compared to the Pitts, now I wonder what all the fuss was about).
At Attitude, although they'll happily give anyone dual in the Pitts, I think they'd expect you to do basic acro training in a Decathlon or Grob before really getting into the Pitts. In fact that's probably your best bet wherever you go. Find someone with a Decathlon, get the hang of acro and do your tailwheel conversion at the same time, and *then* move to the Pitts. Meanwhile, have some fun with dual in the Pitts as well, so you don't forget why you're doing it.
n5296s