The Superbirds were made at Chryslers Lynch Road plant with specific VIN, VON. They started life as a Superbird, not a converted road runner. Superbirds are called "road runner superbird" by Chrysler.
Superbirds had on the fender tag V19 vinyl top code. No other Chrysler car has that code in 1970. And a VON that started with a J and went in oreder like the VIN numbers did. So a car 30 away in VIN would be 30 away in VON also. A13 on the build sheet and window sticker.
Given that Superbirds carry the same RM23*0A VIN layout as regular Road Runners, there is no way to tell a Superbird solely from the VIN like you can with XX29 VINned Daytonas and Charger 500s.
The only exceptions are the 440-4bbl U code 440-4bbl Superbirds as there were, supposedly, no regular production RM23U0A cars built.
You have to have a list of VINs assigned to Superbirds to know which specific Hemi or 440-6 VIN falls in a range of Superbirds. There are plenty of RM23 R and V code Road Runners built during the same time frame as the Superbirds and have similar 150XXX-180XXX ViNs
I'm not going to dig through hundreds of Superbird tags to find a specific example but given that the 999 paint cars have J99 series VONs and not J97 or J98 VONs I'm pretty sure you could find examples of the VINs and VONs not tracking consecutively. Car 123456 with a J97 VON could be followed by car 123457 with a J99 VON.
Given that VONs are repurposed across other makes, VONs used on Plymouth Superbirds may also appear on other makes.
Again, I'm not going to build a spread sheet but given how VINs and VONs generally do not track sequentially for other package cars ('69 A12s, '69 M code A bodies, '70 Hursts), I'm reasonably sure you would find other examples of how Superbird VINs and VINs do not correlate 100%.
