Get it setup on a rolling road, get all these problems discovered and sorted out, IMO thats the only way to be sure/safe in the knowledge the car is 'ok' and your not going to melt a piston........for the sake of what £50-60? for an hour on a RR!

idle - sounds like it either needs ignition timing sorted, idle control valve (forgot the proper name for it on an MFI erst)...air leak...does it start ok?

missing on boost - plug changed/gapped, Ign Timing, Fueling checked...could be other things...

your pissing into the wind really, you could spend £60 guessing and still not get it right....