7-8″ lift will make you very, very top heavy. Big wind come by and oops on the side you go.
Kind of like you said in first post $8,000 by a lot of gas, well $20,000 axle will buy a lot of tires. At the height you are proposing, width is not going to be your problem, the overall height will probably be somewhere higher than 14′ which means you gonna have problems with bridges.
Anyway good luck, I’ll step aside and let others chime in.