hey everyone getting some 1.95 rockers from a fellow user on here.

by the time I get to installing these I will have over 200k miles on the car so im just going to do the springs I've done them on an over head cam engine so this should be a breeze but wondering if it would be a good Idea to go to a junkyard and get some springs and retainers off of an ls6? is this a lightbulb moment or a cheap and dumb idea. just trying to save money as the rockers aren't cheap alone haha. let me know also any tips before I do the install (mistakes to learn from)? also will be doing the valve seals certain method to get those to seal properly or are they pretty easy? and does the rope in the cylinder method work good? because I wont have access to any air do everything I can at the apartment.