Rear leaf lift question

I have a 2007 Tacoma access cab that I installed a rough country 6" lift kit into. The the rear was lifted with 4" lift blocks. Well my problem is it sags like a mofo with no weight so I added a leaf and don't like the looks of it and I have vibrations up the a** which I have had since the lift install was complete. My question is who makes springs to accomplish 6" of lift in order to eliminate the leaf springs I have now and the lift blocks? I was told by Bill at
Alcan Spring that they could build me a set of 6” lift springs for $730.00 with the bushings. So would I need 4" lift leaf springs or 6" lift leaf springs? I was told by another guy if you have a 6” lift in the front a 4” block in the rear that you need a 6” lift rear spring to get rid of the block and the adda leaf. Bill said that 6” lift springs for my truck will have 10” of free arch which I guess I don't understand what that means. Bill says that he thinks that if I were to have them build a 6” lift spring for the rear of my truck to match the 6” front lift that it should level me out and at the worst case scenario I may have a little rake to the front which is what I don't want. Any input or ideas or suggestions?


Thanks