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Assuming you have a 1971 land barge from your name. The 1971 through 1976 models where the largest and the heaviest B-bodies built. With a curb weight of 4,330 pounds empty (but does include oil in pan and five gallons of gas, not found on the shipping weight). That is a lot of mass to accelerate, even with a 7.0 liter LS (though yours could be as small as a 4.3L).
As to who makes adjustable control arms I would look to Hotchkiss. If you are serious about draging it you will eventually need to reinforce the upper control arm mounting points as they are in tension on launch, and with a lot of flogging they will pull loose.
On my 1985 Impala (the ninth and final version of the B-body) I got my weight down to 3,280 pounds by putting the car on a very strict diet. Dropped in a thousand horsepower BBC under the hood and on a properly prepped track while running 12 inch wide slicks I could stand it on it's back bumper while clicking of a 9.39 in what was essentially an old taxi cab.
I used to drive it on the street all the time, but traction was nearly impossible, just smoking the tires for two or three blocks was the best I could do without wide tires and a lot of rubber cement.