Buy the shell from David Silver & the headlight from:
http://store.candlepower.com/ca631quheleu.html
Trevor
Before buying that you ought to check it is MOT-legal, in terms of dip pattern and e-markings (maybe someone one here knows the latest MOT regs...). Also consider the import costs- I had something arrive from the US today that cost $19. As it was so small it was exempt from duty. However, I still got a bill for VAT and for USPS/parcelforce's handling fee, a further $30, plus I have to drive (another $10 fuel) to the depot or there is a $15 delivery fee, all this being additional to the shipping I paid. No wonder the US trade deficit is so bad.
As for running a H4 60/55w bulb, I have done this on my 400 for years using a Cibie unit without any problems, I did used to remove some of the 5w instrument bulbs to make up for it but I have found that isn't necessary. Maybe it is only a problem if you do a lot of slow traffic work and no open road riding.