Calculating Overlap

It's hard to figure the overlap of a solid lifter cam , from the advertised numbers, in a way that is comparable to a hydro.
IDK if there is a way.

Even among hydros you can get tripped up by how various makers determine their advertised numbers. For example, there are two popular starting points; namely; .008 Tappet rise and .006 rise. and then there is .001. From these numbers it is possible to calculate the valve-opening points, but that's a real can of worms. For instance; your arms may in fact be 1.50 ratio, so you are maybe expecting 1.5 x .008= .012 valve open, but once installed, your 1.5 arms may only measure as 1.42 for; 1.42 x .008= .0114 Doesn't look like much difference, but could be 2 degrees at each end, and so your 268 becomes a 264, or maybe less.
For hydros I use the same method that @PRH uses

IIRC, Solids are advertised from .020valve open. But can be whatever the seller wants to measure from.
So how do you compare .020 valve open to .008 Tappet rise?
I know of no way.