Hello
I have just performed this conversion. Took me around 5 hours but that was with all welding etc.
The auto gearbox mount will fit. You need to cut the bracket straight through above the mounting holes and weld it further down. Mine moved back about an inch.
The bracket for the clutch through the firewall is easy to locate. Have a look behind the auto pedal box and you will notice a cutout in the strengthening bracket attached to the firewall. The hole is exactly where you need to drill out. I welded up a bracket that had the tubing attached and screwed it into the firewall.
The only other minor issue was the wiring for the auto. You need to short out the auto selector wire so it thinks you are in park so the car will start. There is a wire that attaches to the selector itself that you just feed to earth. Also, remove the wiring loom from near the starter motor (that also connects to the auto box) and just close the circuit.
Hope that makes sense. Happy to take a few pictures to explain.