My 1963 415 HP M.W. Belvedere 2 door sedan stocker had to weigh 3320 lb. with out the driver back in the 1970s before NHRA added 170 lbs. for the driver and started weighing the car with the driver. It wasn't hard to get it to weigh that much, no radio and removed the heater core, set of Cragar Super Trick wheels with drag race tires with the stock carpet.
I bought another 1963 Belvedere 2 door hardtop and had a Alston 12 point mild steel cage installed and put a cut down Dana 70 in it with the Mopar brand SS 001,002 leaf springs moved into the rear sub frames, added 2x3 sub frame connectors that were .083 mild steel. That car weighed a little over 3550 lbs. without the driver with one plastic race bucket seat no fibreglass body parts with two group 27 RV marine batteries in the trunk and a lightweight 2 gallon steel fuel tank.
Both cars had OEM 1963 M.W. heads, intake and carbs with Hooker headers and no exhaust system, not street driven back then.

actually, the firebird/camaro platform is a semi-unibody design with a bolt on front subframe that the front suspension/steering system attaches to, as well as mounting points for the engine/transmission assemblies.

The camaro's are "f-body"

True, they're like a C body in that regard. Not full frame, but not a conventional unibody either.