[Liv2Fish]

79" - 3/4 for strap - 1/2 sheetrock - 3/4" minimum for total flooring and that will be your finish height. According to my outdated MA 08' code book, habitable basements must have a ceiling height of 7'0" or 84". You may be able to get a "pre-existing non-confirming variance but that's up to your local AHJ.

If you have any duct work or other obstructions to go around, use wood and stick build it. You'll likely find your walls are way out of plumb. Start so the new walls are level and at least 1/4" off of the concrete walls and have the walls sprayed with closed cell foam. That will give you superior vapor barrier and you can get up to R25 in a 2x4 wall.

Steel studs are good but a pain to frame around difficult locations and it makes wiring more difficult IMO.