Thanks for the tip SwallowAmazon, but I've just finished up ordering a load of bits for it. I'm going to email Quattrocorner to see if they have a Bosch Dizzy cap. I'd prefer a Bosch one ideally to keep it OEM, but they seem to be hard to find. I've got the part number 0290 004 035 off the one currently on the car, and I've found a Bosch rotor arm but the cap seems to be elusive.
I'm looking forward to doing the full hit on the car, it's going to do her the world of good.