Trust me, even 10 psi of propane to one of these burners is nothing to sneeze at. I doubt I've ever had to run even half that pressure to get a good burn going. Of course, it's not just the pressure but the pressure at volume that really counts, but I don't have any way of knowing what those numbers add up to.
I'm at 305 ASL, and have BG14s running on the 0-10 psi adjustable regs that came with them. The air shutters are right in the middle of their travel which gives a perfect flame from my usual max heat setting down to a purring simmer.
With as much air shutter travel left to the open side I think you'll likely be fine without messing about with orifice sizing...