I figured it would widen the track width a bit. You'd then have to custom order your front wheels with the appropriate backspacing surely... But would it cause any 'other' problems I wonder?

I think it'd be a super cool build, especially considering the budget you could do it with, to do an entire Mach1 Drivetrain, K-Member, Interior, Etc. Something similar to what JDL1000 has, but with Mach1 goodies, and into a 4-eye

I think that the fact that it's a 4-eye, and using the Mach1 stuff that the Nostalgia / Retro styles would interact really well together and make for a kickass car. Especially in a super low gloss (almost matte) black, with gunmetal Mach1 wheels! Mmmm, yummmy!