Raleigh stem question
 

So I just picked up an old Raleigh Oympian, mid-80's vintage, that's a bit frankenbike-ish. It's currently got some no name stem and flat, mountain bike style bars on it. I'm looking to replace these with a nice quill stem and something like bullhorns. However, sheldonbrown.com tells me that Raleigh require 26tpi on the 7/8" stem. My question is this: is it at all possible to find such a stem that also has a 26.0mm clamp size that most bullhorns use?

Thanks

Classic/vintage or mechanics forums might have a good answer.