I spoke to a couple of people on US forums who were willing to do a retrofit for me, but it didn't seem cost effective due to them having to get some new pattern lights (rather than ship my spares over) and have shipping costs on top of the price of the projectors and labour cost for doing the work.
I decided that I was going to have a go myself - I had the headlights and a HID kit so what could possibly go wrong?!

However, with not being brave I opted for the most basic of retrofits and order some RHD mini H1 bi-xenon projectors from a company in the USA. For those that don't know the minis (as the name would suggest) are a small projector that fits, almost entirely inside the headlight body. Rather than a big square hole to be cut into the reflector all it needs is a 24mm (I think) round hole as there is a male thread on the projector for mounting.

The back of the reflector body also has to be ground flat.

I was thinking about spraying the headlight trim black to give a different look to the lights, but hadn't really considered painting the reflectors until I got the lights apart. One of them was pristine, but the other had quite a bit of the chrome finish off the dip beam reflector.
As this is no longer reflecting anything I decided to mask out the main beam reflector and spray everything else.

The almost finished result.


I like the look of them, and hope that's still the case when I get them back on the car.
I just need to seal the lights back up after fitting, and wiring up the bulbs, to make sure I have the projectors set horizontally.
With these being bi-xenon units they have a solenoid in that operates a flap for dip mean. The bulb stays lit whenever the lights are on but the flap blocks anything above a set level to prevent glare. On main beam the flap is down to allow all light through into the projector. I am going to keep my existing halogen main beam too, so will simply tap into it's feed to operate the solenoid.
I'll keep you posted on performance of the lights once I get them fitted - Fingers crossed for a dry weather Sunday!