Thanks - my choice for hardware
Henry (Raleigh NC)
Having been through a bit more searching, including Van Dykes (where the listed instructions were simply a parts diagram...), I searched the term 'flipper door' on Lee Valley (another great source of hardware). Calling them (that is LV) I was provided answers all my questions and I am likely going to implement their Concealed Door slides, with a set of soft close Blum hinges (as suggested by customer service). Total hardware costs are about $35 plus whatever shipping costs, which is more than the least expensive option, but significantly less than the bigger package deal at Van Dykes.
- LV Concealed Door slides: https://www.leevalley.com/en-us/shop/hardware/slides/side-mount/48629-concealed-door-slides
- the associated hinges also needed: https://www.leevalley.com/en-us/shop/hardware/hinges/european/66792-blum-self-closing-clip-top-soft-close-hinges
The reason that LV customer service suggested these specific hinges is that rather than mounting the hinge base directly to the cabinet, these hinges have a mounting plate that is first installed and then the hinges are slid onto these plates. This eases the hinge installation, and that was a concern; I will have my head inside a cabinet and the rest of me inside a too small bathroom, and will be installing top mount hinges. Ease of installation will make a difference here, even though this is a one-off.
I have not yet determined the final dimensions of the already installed built-in cabinet (opening for inset door and depth of cabinet), but will update this thread when I manage to finish this project.
Henry