[SCOTI]

While junk yard parts acquisition & OE tweaks to fit upgraded/heavier-duty GM parts would work to improve things, it doesn't seem (from what I read) in the initial request for 'suggestions' post that he's interested in that path since he'll be farming out the labor.

New, bolt-in parts would seem the best for the path/option of having a shop R&R suspension items.

Here's another watch-out as well.....

I recommend using parts that the/your installer is comfortable installing & familiar with so there is some 'buy-in' on the work vs. a "We installed what you bought.... Take it up w/the manufacturer if you're not happy w/the install". That possible friction comes when a shop installs something they don't have faith in & its' typically not a good outcome.