lightest a-body??
Just ran across this. I own and race several Mopars. Sounds like someone's going to learn the way I did over the years. Here's my advice:
If weight is a concern when building a car consider this...availability of parts. Ever tried finding headers for a 64-66 A-body? Want to put a big block in one of those? Good luck...expect to do some surgery. What about fiberglass body parts? Then rear fender clearance?
If weight is a concern to go fast consider making it up with cubic inches. My 1971 Duster has a fiberglass hood and front bumper, 500" stroker big block (9.5:1 pump gas), Dana 60, 727, cage and weighs 3,400#'s in street trim. Complete interior and no weight savings or butchery besides the hood/bumper. Ran as fast as 9.94 @ 135 with full exhaust. Tried adding a picture of the car but not successful.
My original unmodified or untouched 1974 Dart Sport 360, auto, A/ C, sunroof, fold down back seat, as well as every option available for that year. Weighed in at 3,800#'s. Engine never had the valve covers off...a time capsule. Smoking the stock skinny rear tires off the line runs 14.60's. Potential...
One thing to consider is a Duster/Demon/Dart Sport. Larger rear fenderwells. Late 1974 to 1976 cars have heavy 5 mph bumpers. I dismantled a late 1974 Duster recently. It had a shock absorber front and rear bumper. 1974 cars normally do not have shock absorber front bumpers. The front and rear bumpers weighed over 100#'s each without the bumper shocks. Best to start with a 1967-73 if weight is a concern. Hope this helps.