Right now is the time to buy material. If you have a way of figuring out how much you need I may still be able to get it for a low price through a connection I have. That's on chromoly tubing. IF we go to war the price of moly will likely double!
I bought 120' of tubing for mine. Snout bars, a pillar, front hoop, dash (under it) tube, with an x- brace. Think Jim had 4' left over. Jim has been building a-body cages for decades now.
I seem to remember some one telling me one of the problems with a cm cage is that over time it gets stress hardened and gets brittle.....though I seen it somewhere in a rule book...Might have been a score rule book....Hmmmmmm.....