My version, the "Markuvator", was built with 2" square 1/4" wall. The upright for the toplink is 26", the toolbar itself is 48". The revision build adds a furrowing attachment to build the hill and dig the planting furrow in one pass. This one worked fine, I just like making stuff and being lazy.

The following is from the ASC website, dimensions of their product,
"The 1-1/4 toolbar accommodates IHC-style wedge clamp & bolts. The frame is 56 outside to outside and the arms are 15-3/8 length on both sides, with 7/8 category 1 lift arm pins."
I'll add, the furrowing attachment will make it a few pounds heavier, and allow it to stand up when parked. I'd get the discs with the longer shanks if I have to replace them. This little thing works really good in a seedbed properly prepared. My gardens were first plowed and then disced and leveled. The resulting furrow created by the discs, is a great way to water with less evaporation. Hope this helps. Mark