Go direct through Grayston then mate.
The bolt is listed in WHEELBOLTS down at the bottom in it's own Ford bit.

FORD GHIA WHEEL BOLTS - CHROME PLATED
12mm - 1.5 with 60° Ghia washer 19mm.....HEX Part No SB31
12mm - 1.5 Bolt only 19mm.......................HEX Part No SB51


This page below take you to their ordering page.
http://www.graystonengineering.com/n...iry%20form.htm

Alternative is to give Rally Design a call. I'm guessing they're going to be slightly more expensive than Grayston though.