Thanks, It's not finished yet, needs a few better photos in places.
Concerning facelift mirrors, I'm assuming they would have a bigger plug than mirrors without indicators.
Compare these 2 plugs for instance:

This is my mirror without indicator plug
And this Is my mirror with indicator plug:

The one with indicators has more wires going into it meaning that the plug needs to be bigger. This is why it won't just plug straight into your car as it is as the socket is too small.
I also don't think you would be able to simply swap the plugs over as there will be too many wires to fit into your smaller plug.
This is why I had to basically scrap the rest of my new fully working mirrors and just cut the indicators off it and transplant them onto my existing mirrors and swap the covers over.
This is why I don't think facelift mirrors will work on a pre facelift as the plug will be too big to plug straight in and I don't think you can simply swap the plugs over. You might be able to squash all the wires into the smaller plug but I doubt it cause they would be in the wrong order plus the indicator wires in the plug wouldn't have power to em cause they would need wiring into the wing panel indicator loom.