There were a series of subtle changes during the evolution of the Ace, many which unfortunately are not covered in Original Ace & Cobra by Rinsey Mills.
The clock was an integral part of the Speedo, then became a separate item approx. Chassis number AEX1083 [?]. Later the clock replaced the ignition switch, starter button deleted to be replaced by a key barrel BEX1210[?].
Turn indicator warning light/s and high beam warning light also changed during history of the Ace.
Tim Isles the Official ACOC Ace Bristol Registrar and ex AC Ace Registrar has be compiling a list of variations and trying to establish date various changes were made during production, by chassis number. This type of information wasn't necessarily recorded
during production.
May I suggest you send Tim Isles a email with photograph of your dash layout and confirmation of your chassis number, hopefully he can confirm accuracy and authenticity of you dash instrumentation.
The Speedo from a 2 litre saloon /Buckland could be the source for a speedo with clock, granted speedo face and calibration will require attention , Tim has details and has carried out conversions in the past.
Good Luck..
Keith ..[
]