727 Tailshaft removal ?

I am prepping to install the gearvendor OD. Driveshaft is out and exhaust is out. I was looking at the access plate for the tailshaft clip and saw that it is not very accessible. I know that I will have to drop the transmission a bit. Car is on a 4 post lift so access is easy. How far can you drop the rear of the transmission without damaging things like the front mounts, transmission cooler lines or anything else? Can I support it on the transmission pan while installing the adapter? Any tips to make this easier would be appreciated. I will go look at the FSM right now.