Speedway G-comp suspension

They have a competition setup , which may be what they are using . It uses a c7 Hubs and uses 275/35r18 tires.
I would think you could get an A-body down to 3k pounds pretty easy .

G-Comp Unser Edition 1962-67 Chevy II Nova Front Suspension Kit

Not that easy to get a 67-76 A-body down to 3000 lbs and be in full trim and full interior.

Have you weighed yours on computer scales?