Congratulations on the MOT - stuff can get expensive in classics
I would leave the WAI to last - I fitted a pipe from the inlet of the air filter to the exhaust on my trip to Inverness last week and measured an average of 55.5 on the trip there, I removed it and got 55.6 for the way back. Neither were correct as I got a higher average for the tank which was 90% this trip but there was no difference I could detect.
I think I may try a CAI instead for more oomph when I do accelerate (I have videos up in the George thread) - when time allows.