It might be lighter than you think- I got burned on a bet with my buddy on his 66/67 Buick Skylark. Big car, all stock, hubcaps to ashtray and that d*mn thing weighed like 3200-3300 pounds. They do have factory 4 link rears and full frames so with aftermarket uppers and lowers, it might hook pretty well. Still a very impressive number from your buddy for sure.

Factory rated it at 3200 lb

That olds is making some steam, how many cubes is it ?

I don't fully remember exactly, but somewhere near mid 500.

Any ideal what the Old's aftermarket blocks are?

friend up the street from me has a '72 (?) cutlass. he had a 496 in it and did some 11:20"s (he may have snuck a couple teens in there) at 123mph, thru the mufflers and pump gas. it has edelbrock heads with serious work, torker intake , AED carb, hydraulic roller, 3.73 rear, turbo 400. it's set up for a bottle but don't think he has any times with n2o. full interior; bet it's at least 3700lbs. think it dynoed 575+hp. currently has a 540 in it, dynoed 670hp. no good times yet with the 540. i would think some kind of power adder would be needed to get into the nines with full street trim. it does take some money to get big performance from these cars, but they can be impressive. i don't think it makes any difference which brand they are you can make those old in-line valve dinosaurs run'

Rocket blocks. good 4 bolt blocks with bigger bores. 4 or 5 grand to buy one. i think big cranks are an issue. my friend had to get a callies billet made; $3500.