b&m trick shift, hurst hot shift, type f, or dexron mercron? what do i use!

Dexron III is type "H" and used in the AOD that uses compound carbon and paper friction surfaces. The C4 uses paper compound frictions and there is no better fluid for it than type "F".
If you run carbon or Kevlar friction materials then you should run a synthetic oil - regardless of what transmission you are using.
The most important criteria is that the fluid matches the friction materials in use.