I have a pair of matched celery 366's that clock at 550 for sale.
I got them with my BP6 from pcnut (when they were in business) years ago. They worked fine when I retired the bp6 a few months ago. (I had them @ 2.1V)
Make me an offer if you want them, I'm trying to clear space.
I'm in Delaware BTW, so shipping should be like $5