All Legal!

Runs a bit better with a new plug but it still bogs down at the higher end of 7k. It's not really a flat spot, it just won't rev past that so I have to shift down if I want to accelerate. Usually it gets past the boggy bit the second or third try but if you stop at the lights it starts over again. It's the same under no load, takes a few goes to get it above 8k.

I'll set the power valves as per the workshop manual, but could it be shitty fuel supply, or something dirty in the fuel line? I don't think it's spark related. The spark looks pretty sparky.