The car you owned should be chassis BE435 (April 1958) and according to the register it still seems to exist, the last listed owner residing in Scotland.
The 100D2 engine seems to have been exchanged for a similar one but a little newer (990 instead of 806). The current engine was in BE1132 originally.
The register states you owned the car since approx. 1965 but by 1968 it was already credited to another owner. Can this be accurate since you mention you owned it in the 70s?
Since you're a member you can access all the registers online yourself by logging into the members area with the username and password stated in ACtion. Next, choose model (Ace) and the register can be downloaded in PDF format.
I'm sure the registrar Tony Bancroft would be most happy with any additional info on the car's history, for instance the name of the person you sold it to.
Jerry
P.S. Only after posting this reply I saw that Keith beat me by a few minutes [
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