I have a modolo 1" quill stem that dates from early 90s that used a hinged bar clamp to allow for easy bar mounting. It is not completely removable faceplate design like the more modern & common 2-bolt faceplate but looks like it uses a couple of links from a bike chain to form a hinge at the front and then also uses a standard single recessed clamp bolt. If you can find one, it would look more suitable on a vintage bike, direct fit for 26.0mm bars and 1" steer tube without adapters.
Here is an example, looks like they were sold as both TTT and modolo.
3TTT Stem 2002 Titanized "Hinged Clamp" 125mm NIB NOS | eBay