Tonight I finished swapping the headlight assemblies on my MK1 with a pair from a wreck i've got. One was a plastic casing with plastic lens and is a genuine lucas. The other is lucas also with a glass lens and metal casing. I've mixed and matched casings and bulbs to get the best from the all the bits I had...which ended up being plastic casing/lens on the drivers side and metal/glass passenger side.
The metal/glass headlight doesn't diffuse the light as effectively as the plastic one and is therefore a weaker light.
My question is 'are the plastic after market assemblies ok? I'm not expecting quality @ $99 a pair!!
 
It would be ideal to find another plastic lucas one if somebody has a spare??? Thanks

I'm trying to get to the bottom of what fits in my Mk2 too.  Seems some 7" round replacement lamps have different mounts at the back (e.g. Narva) to the Lucas ones the car came with, so won't mount to the original trim rings.  I'm interested in fitting some of the newer style lights with clear lenses (so-called Multi Surface Reflectors), as they are supposed to produce a bighter light with sharper cut off.
 
I think the Autopal HL102H4MSR will fit as will the Wipac S6072, but haven't confirmed it yet.  The Autopal ones have (allegedly thin) glass lenses, bulb shrouds and dust covers for the electrical connections, whereas the Wipac ones have polycarbonate lenses, no bulb shrouds (so the bulb is completely visible), and no dust covers. 
 
Anybody replaced their original lamps with modern ones, and if so, with what brand etc.?

I played around with fitting old stock glasses to replacement backings on a square headlight Mk2 a while back, not sure what glue they used on the new ones but it was a bitch to unpick... My Cortina came with one original unsealed and one new sealed unit, had to settle on another sealed one but still looking for an original.
Modern replacements are a plenty on everyones favourite auction site, I picked up a set of modern multi angle units for my RS out of the US complete with angel eye led rings, easy to find but make sure you pay the extra couple of bucks for the proper glass lenses. Will dig them out and take a pic. Fitted up first go. Still unsure if they will look to modern on the car but kept the old ones as a back up.................

Drewdog
I picked up a set of modern multi angle units for my RS out of the US complete with angel eye led rings, easy to find but make sure you pay the extra couple of bucks for the proper glass lenses. Will dig them out and take a pic. Fitted up first go. Still unsure if they will look to modern on the car but kept the old ones as a back up.................

I've been looking mostly on eBay UK (so that I get lights suitable for driving on the LHS of the road), and found a bunch of different ones available, including those with LEDs or halo rings, but most don't meet standards there or here (i.e. 'E' marked).  I don't need the headache associated with non-compliant headlamps, either from the police or my insurance company, so am at pains to ensure whatever I end up is completely legal.
The following link describes some of the legal and safety issues associated with headlamps, although from a US perspective.  Basically, I'm after headlamps that have an E11 code on them, which means that it was approved in the UK.  Australian built MK2 Escorts had halogen lamps with the same marking.  E11 coded lamps will also have an arrow on them pointing to the right (when looking directly at the lamps face), meaning that the low beam is dipped to the left side of the road.
 
http://www.danielsternlighting.com/tech/lights/codes/codes.html
 
Coming from the US, your lamps may have been designed for use there, i.e. driving on the RHS of the road, so it would pay to check this and consider the safety and legal implications of putting them on your car.
 
EDIT: The lamps need not read E11 for UK or Aust. suitability, as "Under ECE and EEC regulations, an item of motor vehicle equipment type approved in any ECE or EEC member country is acceptable for use in any other country that permits or requires vehicles and vehicle components conforming to ECE or EEC safety regulations."  So for instance, the Autopal lights are E4 marked, meaning it was approved in the Netherlands, but have the correct RH arrow on the glass, indicating that they are designed for driving on the LHS of the road.