Those shipping weight forms were juiced on the light side. Another friends 64' Dodge Polara 500 weighed 3900 Lbs on the curb with a dual quad 383, automatic, center console, buckets, full interior and exterior bright trim.
We brought it down to a mid life weight of 3500 Lbs on the curb, changed the cam for a 528 lift, single open plenum manifold, 830 CFM holley double pumper (remember those?) 2" headers and a tight 3200 Turbo action convertor and went 12.90's from a 14.3