I got the MK3 rubber rocker gasket - it was £8 from GSF, the metal/rubber hybrid. You'll need new bolts for it if you have studs because they have a small shoulder on them which stops the metal gasket from sitting flush.
I cheaped out and removed the studs with an extractor, then just used the studs as bolts and screwed them in from the top - they're plenty long enough.
Also, the rubber MK3 sump gasket also fits, again metal/rubber hybrid from GSF ~ £10.