With a caliper or micrometer ... usually your local CSK autoparts store will carry a cheap $20 digital caliper that works well enough to get the job done.
When you look at the cam lobe you see that it has a base circle and then the lobe rises off of the base circle to a rounded peak and then descends back down onto the base circle again ... the lobe pushes the lifter up right.
Well, you measure the diameter of the base circle with your micrometer or caliper ... for example lets say it's 2". Then you measure from peak of the lobe to the base circle and subtract 2" ... that's your lobe lift ... I mis spoke in my first post ... I brain-farted and forgot the fact the lifter is a 1.6 ratio .. the lobe lift from the base circle should be about .285" ... the lift at valve is about .450"
Here's a quick image I made to help illustrate my point:
it's very possible that it is stock. someone told me it wasn't stock, but you know how that goes. CoupedUp, thanks for the diagram. very good info for a newbie like me!