Standard MK1a wheel nuts will fit fine, 1b's will fit OK but are a bit long in the body so stick out a bit and don't look as good IMHO.

MK3 wheel nuts fit fine they are the same thread/pitch as MK1's 12 x 1.5mm
The wheel nuts are parallel, flat faced with a floating flat washer NOT the taper faced type.

I bought a new set from Ebay for around

£20 for 20, but that was a few years ago so are probably dearer now
Jimi
EDIT
These are the type you need
CLICKY
This what they look like fitted


