I would be inclined to try really washing the original headlights first. There is no real way to wash the insides without opening them up, but suspect there is probably a build up of grease on the inside of the glass and the reflector (although fair chance the reflector is now missing some of its silvering).
As mentioned above, after market HID lights are not road legal.
I thought HIDs were acceptable if you have self-levelling suspension and headlamp washers. Its a long shot on an Alfa, but you never know, somebody might have done it
I'm using a self-contained projector beam unit from Hella. 55mm lens, but has an enclosed framework so less liable to get dirty. One thing I found with projector beams though, especially for main beam, is that the spread of light is poor. So now I'm using a pair of Cibie driving light inserts for the mains.
Looking for ward to seeing more pictures of your completed set-up EA!