This wont help Bill right now, but...
We (TrackSpeed) are soon to recieve a shipment of D-Force "CR6" wheels designed for the ITB crowd's desire for just such a wheel. they are based on the d-Force spec miata wheel but modified to 15x6, 4x100, 35mm offset, 67mm center bore, weigh right at 12 lbs plus/minus, and cost $115. if there is sufficient interest from the foxstangs, audis, 928's, and fiesta's of the world, we may make a later run with 108mm bolt circle, or you could try enlarging the lug holes but I can't recomend the latter.
for anyone else interested, contact me or you can also get them through Phil's. I have no objections to starting a 108mm order if enough interest is shown, so speak up!