The cleat bolt spacings during the later (bolt on) slot cleat era were generally proprietary to the shoe manufacturer. For example, if you had a Sidi shoe, you used Sidi cleats. There was a bit of overlap, and IIRC some generic cleats for the common brands were available, but it just wasn't standardized. No reason for it. There were not multiple pedal standards and systems to deal with. Any slot cleat would fit any pedal. I don't recognize these at first glance. Most shoes used one or two bolts.

I think the best path forward is to cut your losses and shelf these, then acquire some slotted cleats intended for the 'modern' 3 bolt Look pattern.