Based on my experience with Jython Drop-in Replacement for Expire 1.x Binding, at least for the expire binding, the oh 1.x binding config shows up as Item metadata. The REST API for dealing with metadata isn’t that great, but I think there is enough there where you could manage even items bound to 1.x bindings.
Anyway, this tool is very timely. I’ve just started looking at how to migrate my Items to JSON. I’ll definitely be giving this tool a try. Thanks!