You are in a weird position. Some of the guys here decide the USG boxes are awesome having never worked out of a truck tool box. No disrespect, but ignorance is bliss. If you've worked out of pro boxes, you may be sorely disappointed in US General. I personally would never own one of their roll cabs. The ICON boxes are ok, but the USG drawers are pretty annoying and meh. It's the latches and the drawer glides, not sheet metal thickness that everyone here talks about. Also the layouts and drawer depths are not what I'm accustomed to.
A cheap used 72'' box could be a bit of a unicorn. I like my 56" box, but if I needed to start over, I'd absolutely bottom feed older 40" KRLs. There are several for sale less than $1000 in my area. There is at least 1 red 40" KRA with an asking price of $600.
Point is, before you spend nearly $2000 (incl sales tax), I'd want to know what the alternative was.
More:
While I love my 56" box, 80-90% of my work is now done with this SO roll cart I bought second hand for $300.

Another thought would be the Edd China approach, where you have one of these for metric, another for SAE, a third for electrical, then maybe another with body tools and spare parts bins. I'd bet for $1700, I could buy 3 or 4 Snap on boxes to suit my needs. That might actually make more sense than a big base roll cab. Hit me in the face with a pie, I'd probably buy used USG carts and have 4+ boxes for less than $1000.
Just food for thought before you pull the trigger and possibly have regrets. GJ raves about HF and USG, but hate to say it, no offense, it's largely an uninformed opinion. I think they aren't really
nice boxes any of them. What's great about them is that they are cheap and readily available. Once one of those attributes is challenged (i.e. prices pushing over a grand) I think there are WAY better alternatives. At least in my neck of the woods. Hope this helps