A grey morning but have decided to press on regardless. Dismantled the side wall and trimmed it in a couple of places. Noted that the top lip has to be deep enough to take the both the covering and the piece of rubber that runs along the inside of the wing which I haven't attached because it will probably need to come off for painting. Allowing for the rubber trimmed the top piece down slightly. It's still a little high in places but it might be easier to trim or file it in situ once it's bolted onto the car again.
The earthing strap could be refitted again and was thus able to start the engine. To my horror two minutes later there is smoke billowing from the drivers side of the engine bay. The oil pressure hose connecting into the dashboard was touching the exhaust header and has melted through allowing oil to pump onto the exhaust header. Powered everything off and bound the small hole in the tube with a double layering of insulation tape since I couldn't find my self amalgamating tape for some reason. Taped the tubing to the binding around the wiring loom to ensure that it doesn't come adrift again. Restarted the engine, the gauge is still working on the dashboard and the repair didn't appear to be leaking. Will bind over it with some protective fabric tape at some point in the near future.
Dropped the starter motor out of the way allowing me to drill the last few holes at the front of the engine bay side wall and bolt it in place. Also added a bracket which keeps the wiring loom clear of the alternator.
The indicator housing and cover finally arrived in the post so started work on finishing the electrics namely putting the headlamp into place. Fitted the lamp and cabled everything up. The headlamp does work, but it seems very dim compared to the passenger side, forgot to check full beam will need to do that next time I'm down there. Will also need to adjust the alignment.