I just installed a Hellwig 73-76 K-member type sway bar. Installed it in about 20-30 minutes in my garage under jackstand and taking only one wheel off. Just make sure to jack the car 14" or so in the front to thread the sway bar in (73-76 K-members). I like tighten the end links 80% on the jackstands. Then leave everything a little loose until I get the car back on the ground. The sway bar with sort of center itself. Then final tighten everything.
For the 66-72 sway bars, you shouldn't have to even take the wheels off or jack the car that high.