Shackle flip is a good way to lift your truck , flexes well , and you don't have a block to spit out .
As for towing , its generally considered a no-no for anything really heavy .
Personally , I have towed a 78 K5 body tub on a 2000 lb trailer and it didn't feel funny at all , and loads of trash that weighed as much as a couple ATV's at times .
I wouldn't want to tow something as heavy as another truck however , thats what tow rigs are for .
How much weight do you estimate your gonna tow ?