Andy
If you have trouble with 165 x 16" Avons rubbing on the rear wheel arches, you need to check your transverse leaf spring is correctly located, that your spring has not flattened and the bushes in the rear spring and the rear geometry are 100%.
Granted each Ace is hand built so each side can differ slightly, also Aces often left Thames Ditton with unequal camber on rear wheels.
You should not have any problem, however if cornering hard two up you find you are just touching ( blistering paint on rear asrches ) suggest you ease the rear wing out a millimetre or two with a ali packing piece.
If you pull out too much you will pull the leading or trailing edge of the wing in as the edges are wired.
Rest assured from experience and many thousands of miles by numerous ACOC members you should find the Avon Turbosteels transform your Ace, experiment with tyre pressures subject to use..... Road / Race. One up / Two up.
I'm running 27psi front 29psi rear for road and increase pressure for track according to track temperature & climatic conditions.
Ace look much better on 16 " wheels , What diff ratio are you running? and do you have overdrive ??
Hopefully other Ace owners can give you their opinions regards Michelins and / or Blockleys.
Enjoy
Keith