I had some more time today, and tried going through assembly / maintenance steps in my head, and I discovered some issues.

Once the Z axis is mounted, it is no longer possible to adjust the rails or the sleds.
To address this, I switched to the wider HGW20CC sleds and added access holes through the front plate so that they can easily be adjusted. I also changed how the spacer plates for the rails work, so that they can be adjusted through the front plate as well.
I also added extra holes to the side plates to allow direct access to the grease nipples on the sleds.
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As for the X and Y axis, I flipped the FF bearings, so that I can install / remove the ball screws without having to disassemble half of the machine...

In terms of motors, I'm back to my initial choice, the Lichuan Nema24 LC60H2127 / LC60H2102 motors with LCDA86H drivers. For some reason the shipping cost on their aliexpress store has come back down to reasonable levels. Let's hope it stays that way until I'm ready to order...

For timing pulleys, I want to give these clamping type pulleys a try. For testing purpouses, I think I'll just order a couple of them and mount them onto some precision rod I have laying around, to test runout and how much torque they can take before slipping.
If they work well, I'll probably go with 25 teeth htd 5m pulleys.
Not sure if I should use 15mm or 20mm belt width though.

As suggested, I also modified the gantry layout from a single 160x80 profile to 120x80 + 160x40 profiles (L shape)
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