MK2 seats are not a direct fit, but close enough. Basically you'll probably find the forward/back handle is on the wrong side of the MK2 seats, depending on what year the cabby is. Post 84 I think they changed the floorpan so you can fit MK2 seats directly.
At the back, its gonna take serious effort to get MK2 seats to fit, probably almost impossible!
Dont even bother trying to get the doorcards to fit, it aint gonna happen
Mk1 cards are completly flat, and MK2s stick out a fair bit! On the plus side, this makes MK1 cards dead easy to make!
Edit: I have a set of black vinyl door cards, and possibly a full set of mk1 seats going if you're anywhere near Bracknell