I did a 3" to my '75 c10. Not too bad.
Here is what you are looking for; SkyJacker lift systems.
There are at least 3 options, two 4" kits and one 6" kit. They are all basic kits new leafs in back and new coils up front.
Sumit Racing part numbers
4" SJA-C140AKS both front and back springs
4" SJA-C140AK I think that is only one set I am not sure
6" SJA-C160AKS both front and back
I think that the numbers after the SJA are the same as the SkyJacker part numbers.
Hope this helps.
Zach