Confusion over Harrison wheel offsets

[sambo]

As if wheel offsets weren't enough of a mystery, I relate to you the following... I've ordered a Harrison chassis/body kit with R32 Skyline IRS. That's Nissan/Ford rear stud pattern and Commodore/GMH front, no problems there.

The following numbers relate to the maximum distance from the bolt up face to the outside of the rim, or frontside offset as I have read elsewhere. Assume 17" wheels, 8" front and 9.5" rears...

Warwick Harrison informs me that I need 95/135mm front/rear.

Doug Pearce, who has worked on several Harrisons down here, says 75/100mm front/rear.

Pasquale Piccioli, maker of Millaz wheels and who has supplied several sets of custom sets for Harrison kits, says 80/135mm.

So from 3 knowledgeable people we have a variance on the front of 20mm and 35mm on the rear. These are not small numbers!!

Can anyone with Harrison experience shed some light on this for me please? Millaz seems like the safest option, since he allows you to pre-fit the wheels prior to final welding. However, his price is around $3500 (unpainted), whereas I'm seeing them advertised in the States for $1500 USD. It would have to be at least $1000 less to import them, even after adding freight and GST. Of course there's the risk of getting the wrong offset.

Thanks in advance,
Paul