Will a lift Decrease Value?

[dmigura]

This may turn in to a long story, but need to get out what I am thinking. I have always wanted an old Jacked up chevy 4x4. An looked for one for about a year. I am from South Texas and rust is bad so everything in my budget I found was a bucket. Until I found a 1970 one owner 80 year old man. Everything is original, besides fresh paint, and a new wood bed. there is no rust, and the motor is original and runs and drives great only 70,000 miles on a 35 year old truck. I paid $3800 for it and thought I got a steal. Anyway now I am scared to put a lift on it. For one I dont want to screw up driveability or anything else. But the main reason is I dont want to decrease the value of an original classic. I wont wheel it much at all, just want to know what it might do to the worth. Also did I get as good of a deal as I think. 1970 1/2 ton 4wd 350 standard AC NO RUST.