Sand blasting is just a quick way to remove paint and the sound deadening material. We do it here all the time generally just to remove the paint and any other exterior imperfections like old body filler. It's a good cleaner, but offers no real weight reduction unless used in the interior, but it gives you a great bare chassis to build on.
Acid dipping actually affects the structural integrity of the chassis by thinning the metal. Its a complex situation and is based on how thin you can go, or want to go. Most cars that do this use a roll cage to rebuild the structural strength. On a street car I'd advise to leave the chassis alone and have the attached panels, doors, trunk, and roof it can be removed, done. When extreme the metal is now egg shell fragile and serious impacts will result in F1 like metal carnage. Having people just leaning on an acid dipped car can be a problem. In my old SCCA autox days this was trick to cheat because they never weighed the cars up to a certain class. So people would take their street cars and have them acid dipped.
