3/4 ton spring question(s)

[bigcarguy]

I know I only have a 1/2 ton, but the springs are sagging and I'm gonna be replacing them here in the next few weeks. I just wanted to know if 3/4 or even 1 ton springs (front and rear) would fit on my 81 C10 (2wd). Also, I read on here that a 3/4in spacer would give about 3 inches of lift for the front, where can I get a pair of 3/4in spacers? I assume it'd just take a 3in block in the back to level it out, right? Sorry for all the questions, I just wanna go ahead and get all the suspension stuff done at the same time. Thanks.