InDesign book split in two - page numbers

The short answer is that ID's conventional page numbering will handle the first 120 pages, but there is next to no way to make it work in any nonstandard or non-linear way. So you aren't overlooking anything. 

The usual practice for reversed or 2-up or right-page-only numbering is to create a Parent page text flow where you want the numbers, then dump in a text file with the numbers. It's just text, so you can do anything you like. (But these won't be handled as page numbers by indexing, TOC, etc.) Ask away if that doesn't put you on the right track. 

If, though, you are talking about a flip book like the old Ace Doubles, you can use a conventional layout and seam it together in the output PDF, or other ways. You do not normally try to do both halves in one source doc.

And a heads-up: many book printing services won't accept nonstandard layouts like this. KDP in particular is stubborn about page orientation, numbering, etc. 

Another Déjà vu?? Or the other poster needed pages to intersect? 

If you'll be giving this document for someone to print - just prepare two separate documents. The place that will be printing it - will take care of "the imposition". 

How are you reproducing the book? Are you sending it to a commercial printer? Are you printing it on an. digital printer? Are the pages printed as spreads?