[Jim Colman]

greasemonkey,
Don't discard the notion of a fiberglass inner liner or "tub" for your replica. This type of construction makes the car quite stiff and stable. It does add weight, however the car still weights much less than a traditional vehicle. My ten year old Midstates replica had many thousands of miles on it, including several "un-scheduled" trips off the race track. The car held up extremely well and the body looked just a good as the day it was first built. Fiberglass is also a better heat insulator than aluminum. Your feet will appreciate it.

Cheers
Jim