reason I ask is that I've got a set of 19x8 and 19x10 wheels on my Z right now and was thinking I might be able to use them. Same bolt pattern though I'm not sure of the offset specs. Pic of the rims:
I'm not sure how the design would look on the mustang... might be a bit too modern. But they are 2 piece forged wheels and pretty damn light for 19's.