Rear suspension design

[70Longhorn]

All the good work around here has got me fired up to get going on this Longhorn project. I thank you all for that!

I'm starting my rear suspension design and am looking for some tribal knowledge. Does anyone know the height of a C-20's center of gravity? Ok, I know that's like asking the size of a gray suit, but there ought to be a general rule of thumb out there. Maybe it's about the height of the crankshaft at OEM ride height? Maybe it's lower than that? Higher?

I just want to get into the ballpark to get a good baseline for anti-squat/anti-dive geometry, and roll center calcs.

CG in X and Y are easy. Anyone know a good Z number?
Thanks!