the gearing could be anything, guys. it was 86 after all. ya gotta check to know for sure.
as to the lift, be sure to read up and buy a kit that actually includes all the parts. just because it's sold as a "kit" doesn't mean it's complete.
your mpg will always drop with height and bigger tires, but it's a Jeep, no one buys it for the miles per gallon. it's all about the smiles per gallon.