[TUHS] PDP-7 and Interdata 8/32 Bell System UNIX Installations?

[segaloco via TUHS]

Are there any documented or remembered instances PDP-7 or Interdata 8/32 UNIX being installed on any such machines for use in the Bell System aside from their original hosts?  Along similar lines, was the mention of PDP-7 UNIX also supporting the PDP-9 based solely on consistencies in the architecture or did this early version of UNIX actually get bootstrapped on a real PDP-9 at some point?

My understanding of the pre-3B-and-VAX landscape of UNIX in the Bell System is predominantly PDP-11 systems, but there was also work in the late 70s regarding 8086 hosts as evidenced in some BSTJ and other publications, and there is the System/370 work (Holmdel?) which I don't know enough about to say whether it technically starts before or after UNIX touches the VAX.

Thanks for any info!

- Matt G.