"The Gougeon Brothers on Boat Construction" Table B-1 ... lists the following properties for Okoume/Gabon

Specific gravity = .37
Modulus of rupture (static bending) = 7300 psi
Modulus of elasticity (static bending) = 1.14 X 10*6 psi
Compression parallel to grain-maximum crushing strength = 3900 psi
Side hardness load perpendicular to grain = 380 lbs

The reference should be available on the net as a free .pdf ... that's how I got mine.

You'll find a little information about the specs the plywood has to meet in the BS1088 and BS6566 standards.

The basic BS1088 info ... including plywood thickness vs weight per sheet can be found here ... http://www.glen-l.com/wood-plywood/okoume.html
Note that BS1088 applies to "plywood made with untreated tropical hardwood veneers" ... not just Okoume ... so I'd expect some variation in the numbers depending on the species used.

Ken Blanton