Question,, will the US spec IS300 headlamps, fit in the UK spec IS200...

Dont see why not

There'd be the small matter of them being left hand drive ??

ahh yeeehhhh... err can they be converted then...

Order UK ones then

I have a set sitting in my room for monthes cause the cluster isn't the same as the IS200 one. + it has 2 sidemarker bulbs + it is HID
I just couldn't make them enter in place of the IS200 ones

US headlights are not LHD, they point straight ahead

so theres no-way no-how that the US spec HID will fit in the UK spec

with a little work and motivation, I'm sure you will succeed in

and what problems with MOT's are there with having the beam point straight out

To do HID headlamps properly you are looking at a least a grand because of the auto levelling computers.

But in saying that, we are currently looking into getting round this

watch this space