I have a 87' k5 with stock leaf springs and 4" blocks all the way around. I was wondering where i could get acutual 6" leaf springs so as to replace the blocks. Thanks.

You can get leaf springs at just about any spring shop.
I got leaf springs for my '74 at a local spring shop ( located through the phone book)
My '85, I ordered the B&D 6" lift springs from Lordco, which is just a local parts store.