Portrait pano head
If I were only going to shoot in portrait orientation, I would probably go for something like this.
Lego turntables pop apart quite easily so the slide would be supported on a bolt right through the upright and the turntable would only be used to provide rotation.
A metal sleeve through the wood or small ball bearings at each side would have to be provided (not shown in this sketch) to mimimise wear on the wood. Mind you, the frame is the cheapest part and could be replaced when worn out.
There would be a risk that the top of the upright might break off (letting the slide and camera fall to the round) so it would be adviseable to provide a metal plate on the back or sides as reinforcement.
I built one like this using 25mm square pine and a coach bolt in a tight-fitting hole to hold the slide in place. I drilled the hole by eye (no drill stand available) and it ended up squint! Worked fine though.