904 help

Looking to rebuild a 904 out of a doba for my Lebaron. But have some questions.

1. Do I need to worry about tailshaft or transmission overal length?
2. How can I determine what series of 904 it is for parts without the tag?(missing)
3. What rebuild kit, shift kit, and upgrades do you guys recommend?
Trans won’t see more then 450 horse 450ftlbs and 3:55 gears and street tires.

I’ll worry about converter once I decide on my engine combo.
Thanks in advance guys!!
Author: TheSkunk