72 Chevy K10 Leaf springs/ Shocks

[89Chevy]

Hey got a random question that might be pretty dumb. Attempting to do some work on my K10 suspension. I have to replace my leaf springs/ shocks and not sure if i have to size them out before getting new ones? I know the truck currently has a lift but not exactly sure how or if I have to measure it. Also any recommendations on brands for Shocks and Springs. It’s my everyday driver, but I use the truck 4x4 for camping in mountains and crawling in sand.