All of the exotic wood I come in contact with is FSC certified. We legally cannot import it through our flooring mills if it isnt FSC certified. (I know there are global organizations that deal with exotic timber too; I do not work with the importers or mills directly however.)

A wood piston could be a fire hazard, but not likely to burn much if the right specie is used. I've tried burning saw dust and sanding dust from Spotted Gum flooring (a greasy Australian specie) and it would not burn very well at all when compared to burning sawdust from a domestic wood like oak or maple. Totally different animal.

Ironwood or Lignum Vitae is about the same hardness as Ipé. I'd assume based on its description that its a greasy wood like most other South American/Central American species.

I think it would work as a piston - As far as the wristpin goes I could press-fit the pin in the would-be wooden piston with teflon caps on the ends.

If I had access to an endmill, I would cut a piston and try it in my old Fox .40 series V since the piston and sleeve are wore out and parts are not available for it anymore.

I'm really curious to do something like this just for S&G's but alas, my tool stash is lacking...