Time for an update.
I've been sourcing a few parts to return the car to a completely stock appearance. First thing was to remove these larger side indicators that had been previously fitted.

Bought some original side indicators from the UK, much better...

Next thing was to track down an original amplifier to go with the original stereo that came with the car. I managed to find one on Ebay UK, so I took a chance on it being in working order and bought it.

Time to take out the aftermarket Apline head unit and cassette holders that had been installed. I'd already taken out a couple of screws before taking this photo, hence the gap at the top of the cassette holders.

I was worried about what might have been barstardised to fit this stuff in, but thankfully whoever had installed it had done a good job of it, and left the original wires in tact along with the original bracket, aerial and wiring loom to connect the amp and stereo.

Had to screw the bracket back into place, and then it was ready to take the original stereo and amp.

Connected everything up and then slotted then into place. Reconnected the battery and with fingers crossed fired it up. Much to my delight it came to life and everything seems to work. The finished product.....