With my tall (one liter) Paterson, I can develop four rolls of 120 at a time (load two, one after the other, on each reel -- not difficult, but practice a couple times with sacrificial film before you do it with images you care about). In your case, that would still be eighteen tanks, or about nine hours (not counting drying time, since you probably don't have 70 pairs of film clips or space to hang that many rolls simultaneously). I've seen stainless tanks on eBay that would take up to eight 35mm rolls (or maybe four 120), but that's not really a step forward from four in a Paterson, and you have to work in the dark and agitated by lift, tilt, lower instead of inversion.
There may be a taller Paterson that would let you load three reels set to 120; if so, with double loading, that would get you down to a dozen loadings to get through your backlog. If you have a drying cabinet that will hold six rolls, you might be able to do all of that in one (long!) day.