B-Body Diff, C-Body Diff, Wheels/Tires

http://sjvhk.jabzm.servertrust.com/ProductDetails.asp?ProductCode=FST-F14

This would be the wheel I think I would go with.

I saw a set on a Factory Five GTM and I love them. The Offset I feel could be tailored just enough to make everything work (RMS Front + whatever works in the rear)

I had hoped to go with a set up like this:

Front:
18 X 9 (Offset TBD)
BF Goodrich GForce T/A KDW
275/35ZR18

Rear:
18 X 12 (Offset TBD)
BF Goodrich GForce T/A KDW
335/30ZR18

Anyone have similar sizing on this type of wheel/tire/differential combination?