Malcolm,

You can find some data like you describe at http://www.thag-o-mizer.net. A little basic math is required to extract everything possible from the data presented in the tables, but you can use that data to come up with some reasonable approaches to estimate the weights of other lay-ups not listed. Keep in mind that a lot of what you wish for can be influenced by the conditions and techniques used while making the samples. For example, how much epoxy balsa will absorb compared to mahogany may vary with the resin viscosity, which is influenced by the formulation, pot time, temperature…

Sam