Johnny Lightning's Lincoln is reasonably close--well, it's in a ballpark near mine.
Still working on the front end of the Mark III, trying to hash out the shape of the fenders. Had to go looking for more source photos of Lincolns. Ended up at a page comparing the Mark III and its Cadillac competition with lots of usable pics and one hell of a long loading time.
Good thing I'm not on dial-up anymore. That site would have taken days to deal with. Just grabbing the link to paste it here made my computer choke for almost 2 minutes.
So anyway, the Lightning car is somewhere near right for suitably vague definitions of right. Still cheaper than finding a full-scale Mark III to measure.