Guess what I did! Searchbarred. Don't complain.

And don't act like every question is answered in the wiring thread (plus I need a more immediate answer).

What pot value would go best with a P90 in the neck position of a Les Paul (standard wiring): 250k or 500k. I have both right now and once one goes in I won't feel like rewiring it for a while so I'd prefer to be immediately pleased with it.

Going for an (early) Iommi type tone. Vypyr amp for now but will be upgrading to a nice tube amp over the summer so just pretend the amp is a good one.
I'd go with the 250k. My Les Paul's P90s use 300k, and they're plenty bright. 500k would be pretty sharp sounding, I think.