After pondering this, I think I'd like to have my brain studied to help understand the biological basis of gender identity (like the BSTc study), adding to the body of evidence that we're born this way and cannot change it. That might help trans children avoid being mentally tortured by nuts like Kenneth Zucker, and increase awareness and acknowledgment amongst the more educated cisgendered demographics.
The rest of my organs will be donated. (Can I request my lower bits be donated to an FTM?

)