saddle height with cleats
 

Normally ride spd SL (yellow) cleats with carbon fibre soled shoes
Have an event soon where I want to switch to shimano MB shoes with recessed 2 bolt cleats--? how do I work out the saddle height for this combo\TX

Logically.

Figure out the sole thickness of each shoe, whether with a home made caliper, a real one, or through a Google search.

Figure out the pedal axle center to sole of shoe distance with something like a ruler or through a Google search.

Adjust saddle height appropriately. This assumes you want the same height - for mtb/cross many people drop their saddles a touch (I do for mtb, never done cross).

As long as these are within +/- 5 mm, I would not touch anything.

5 mm raise the saddle up.