I have some - probably not a lot newer than the old wooden originals - VERY heavy duty and large metal variants of this exact design. I don't need them very often but dang do they work a treat when I do. It's definitely tempting to make some wooden ones (can't ever have to many clamps hah). The exploded breakout diagram of these is pretty nicely done and very cool.
I think it would be cool to find an old clamp like this. No idea who even made the thing or if it was designed to be a machinist's project. The clamp screw body was cast but back in the late 1800's and early 1900's casting something like that wouldn't have been as out of reach as it seems like it would be now.
The bosses and gussets on the head of that one are nice! I imagine this one has to be a metal bar based on the design.. I could see marrying the two designs with the tail end from the spanish one and the head end from your other model.. hrmmmm..
Yeah. I'm sure this one is all metal. You're right about combining the ideas. Certainly the sliding jaw could be located with a pin through the wooden bar.