Chris and I recently swapped the auto trans on his diesel 80, I would imagine that it'll be a similar job on a petrol.
We found that removing the gear sticks and their associated interior trim, gave good access (using wobble extension bars through the hole in the transmission tunnel) to the tricky to reach top bell housing bolts. You'll also need to support the engine, otherwise it'll pivot around the engine mounts and fall backwards against the bulkhead when the trans is removed.
Once we had the box down on the floor, we removed the front bumper and connected a bridle to both the front recovery eyes and used the engine crane to lift the front of the 80 quite high, to allow us to slide the box out under the chassis (we used two cut down scaffold poles wedged into the bulkhead outriggers to support the load, so that we weren't working under a suspended load).
It's heavy and awkward work swapping the trans, I would say it's a much safer job if there's two of you on the job. Out of interest did you buy the 80 with a dead trans?
Good luck and happy spannering!