If you're not going to be putting a lot of money into it I would just as soon put in a LS tranny or GSR tranny. They are more than strong enough and can come with LSD for a couple hundred extra. I don't see any reason for a c5 tranny on an a1.
They are cheaper and easier to find, and should bolt right up.
But as for parts I'm not sure.
There are kits on the net places, but I'm not sure where. Search google.
You'll have to drill the firewall for the clutch pedal.