I was planning on an end switch mounted on each of the 3 Z leadscrews which are fixed to the bed.

This is just to get them back into a known state.

I still plan on Z probing to set the final first layer height / mesh bed level etc.

I've designed for an induction probe (Prusa's) but I'm also considering putting a BLTouch into service.

I guess I'd need to to an offset for the probe - which for my induction probe is X-27 Y-7 from the nozzle tip centre to centre - but I've not got that far yet.