I say pull the trans because there is like 8 bolts holding the ting to the cross member versus having the hassle of taking the starter off to undo all the TC bolts and trying to get all the bell housing bolts...
The whole point is to avoid having to fist all the small spaces in and around your motor.
A couple mounts and the trans and motor is loose. It definetly is a lot of weight. We bent an engine crane taking my LB7, trans and transfer case off the back of a truck. But it can be done, just need a bit more HD unit.
With an engine on a stand in the garage, the headgaskets could be done in 4 hours. I'd even venture to say that if you had two guys that knew what they were doing, you could have the motor out, headgaskets changed and back in all in one day. Thats a stretch though.