Some progress today. Fabricated a plate for the handbrake to be mounted to. It's made of 4mm aluminium plate and is bolted underneath the car and supported by the two tunnel chassis members. It's not fully attached yet as I need to get completely under the car to finish it. I measured up the throttle and clutch cables. The throttle cable is going to be made by my own fair hand. Time for an order to VWP. I am going to contact an industrial control cable manufacturer to get a quote for the clutch cable. If it's cheaper than the other options then I'll go for it.
I fitted the front brakes as well and went back to the longer goodridge hoses. They are fitted directly into the caliper and with a suitable attachment to the upper wishbone, should provide no contact with the spring or wheel. If the MOT people don't like it, it's not that hard to change back to the old idea of using the standoff brackets.

The PX600 air filter is an enormous sausage! Unfortunately the baseplate I was sold as a nearest fit actually doesn't. I should be able to return it and either get a blank one or my money back. I'll take a template of it in case I do return it for my money back, then I can make my own baseplate (which I should have done in the first place but I was being a lazy arse)
The car was running again today, starts on the button (with a touch of choke) and idles lovely up to temperature. The addition of the PX600 makes it look a little more serious :-)