I've seen another Mach with white stripes, but left the rear spoiler black. I'm not sure how a white spoiler on the back would look, but I don't it would give you the look you may want.
The stripes might be ok, but I dont think the spoiler would be. I have seen silver and gold before and they looked good. The gold was like an old GT 350H. Didn't some of the 69/70 black Machs have red stripes?