Okay, where to start here? If you don't have a floor jack, the roll away 2 or three ton kind, get one before doing anything more involved than changing a tire. They are less than a hundred bucks most anywhere. Get a wide saddle, like 4 inches or more. And buy a set of jackstands. The better quality, the better likelihood you won't get crushed to death. If it doesn't give quite enough lift, lay a 2x4 flat on the saddle.
Once the rear is lifted up, no problem, there is no trapped tension as with the front coils (captive).
Coils will drop it okay, but then it takes a bit of aligning to get the camber alignment right. If you want to lower the front 3" or more, consider spindles. (Although a bit more costly. Springs are an acceptable method, I just recommend a spindle drop.) Just don't cut the coils an forget about them. Buy new lowering coils.
Like stated above, put in new ball joints while you have the front end apart. If the ball joints are riveted on, they are original. If bolted on, they were replaced, but unless oyu know the history, it would still be a good idea to replace them while it is convenient.
I like the line from the Metallica song. And if only you had the money you put into those shoes to put into your truck...
'79 GMC shortbed 454 th400 14 bolt FF NP205 Dana 60
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