thanks carl.

i don't think the epoxy makes too much difference in stiffness. i've found the best way to get the stiffest part is to alternate laying down the fiberglass pieces at a 45 degree to each other. if you lay down the all of the fiberglass pieces with the same orientation the part is stiff in one direction but flexible in the 90 degree plane (make sense?). that cross pattern gives the best all around stiffness.
i'll use either West Systems or Z-Poxy Finishing resin depending on how much epoxy i think i'll need for the job. i generally use Z-Poxy for the smaller jobs since i can mix a smaller amount than the WS pumps put out.