I've done a few 4" lifts using Skyjacker springs. I use the setup without rear blocks. You'll need a raised steering arm and also an adjustable drag link which no one that I can find makes one a 72-93 Dodge. Skyjacker sells one that they say is a Dodge but is a Ford and needs to modified to work properly.
I've also done 3" body lifts. Need to lower the radiator on the core support and modify the bell crank if it is a manual. Rework the brake lines and steering column a bit. Raise the bumpers. Doesn't effect the exhaust.
You could use new front springs with the factory 4" rear blocks.