To get a more actual axle to crown measurement, measure from the center of the rounded bit of the fork dropouts to the join where the fork meets the headtube on the bike.

Usual suspension fork sag meaurements are 25% or so, so you would subtract something like 12.5-15mm sag for your 50-60mm of travel fork to be a more real world ATC measurement.

Or if you really want to get tech, zip a cable tie around your fork, just above the dust seal. Carefully get on the bike without bouncing it or any sudden moves while supporting yourself against a wall or other object. The suspension will sag to where it should be at rest. Get off the bike carefully and when the fork extends, zip-tie will stay where sag settled out. That space between the tie and the top of the dust seal -- subtract that from the static ATC measurement to get real close to your stock geometry.

Then match that up against available rigid forks.

Longer crown-to-axle measurement will raise your headtube, lengthen trail, and relax the steering angle. It will lead to slower steering, larger turning radius, more straight-line stability.

Fork offset will also affect steering...