beefing up the chassis?

[HGturboT]

I just read about Cal Hartline in GMHTP and how he had a stock chassis. Am I miss understanding STOCK or is it really stock, basically would I have to upgrade my chassis for a mid to high 9 sec buick and if I wouldn't have to are there any good tips on reenforcing it(when I get quicker) sorry for all the questions, just trying to get a good understanding. thanks again