You're going to find out that a flip kit puts the center section of the rearend extremely close to the bed floor and the back will be really low.
They look super cool with a flip kit, but you will need a frame notch and maybe a bump in the floor.
Blazers are different in this area, compared to the trucks.
I've lowered two of these.
A '79 and a '82 2wd blazer.
My '79 got drop shackles and I removed all but 3 leaf springs.
I wouldn't suggest this.
My '82 got lowered leaf springs.
Your rear leaf springs should be the 52" version.
www.performanceonline.com sells them.
Also if you add a drop shackle for the rear leaves, the right side gets into your fuel fill hose.
So that will need to be re-routed.
I would stick with a 5" drop leaf spring by itself.
The front will be just like c10 trucks with the normal spindle/spring drop.
Good luck.