Avid Ball Bearing 7 front alignment

Hi all,

I'm having a problem with the set up of my front brakes and was
wondering if anyone wiser out there had some advice - especially since
I can find no trace of a technical help email address on SRAM/Avid's
web site.

I have the following set up:

Rockshox Revelation 426 Dual Air Forks.
Avid Ball Bearing 7 Mech front discs - 185mm rotor.
Halo Combat front wheel with non branded (but IS rotor mount) hub -
looking further into Halo's website I think it is an ID hub.

The problem is that when I fix the Avid caliper to the fork mounts in
the inside of the fork leg (between fork and wheel) then the rotor sits
between the caliper jaws - but not without touching/scraping the edge
of the metal housing of the jaw itself - i.e. even with the pads wound
all the way out the rotor rubs on the caliper.

Going against the Avid instructions and attempting to mount the caliper
on the outside of the fork mount produces the obvious result of the
rotor not coming anywhere near the caliper jaws - its about 8mm out. I
thought about puting shims/spacers between the rotor and hub but I'm
dubious about having that large a spacing set up. I'm also not sure
(without trying) if this will even work space-wise.

Any ideas? I've tried playing around with the more subtle positioning
of the two caliper mounting screws to try to move it as far away from
the disc as possible while still being mounted on the inside of the
fork leg... but all I can manage is a barely fitting rotor that offers
no beaking power at all (pull levers to their full extent and the
moving pad can't reach the opposing stationary pad with enough force.)

NB: I've set up the rear brakes fine, and have set up the exact same
brakes on another bike without any hassle.