A855 - 5 Speed

I'm finally in a position to get the hot rod I have wanted for 20 years. Because it will be a driver, I was thinking about the 855 as an OD option...but not after reading this shitshow! Tremec, please.
Right. I have "about" a 95 Tremec T5 out of a Mustang I am gathering all the parts to put in Vixen, my 64 Valiant. I've compared all the ratios with the 903 3 speed and it should be one hell of an upgrade.