There's a list of all the original K3 engines in Mike Hawke's "K3 Register". All except K3751 - the original prototype - have engine numbers with an AK suffix. K3751 had KEX3 - K EXperimental, presumably.
However, the engine numbers are random and - except for K3030/630AK - never remotely tie in with the chassis numbers. Nor are they in any logical order - 1AK was fitted in K3016 for example, while the first production car, K3001, used 18AK.
Work has been carried our on all the chassis files by past and present committee members. It would be possible to determine, with a little work, which engine originally went to which chassis. However, because of the number of new parts available it possible to make a new car from this information and then the real original thing turns up. I do not think this information will ever be made readily available via web sites etc and put in the public domain.
If you have a specific question or reason regarding a K type number etc I suggest you contact the Triple-M committee. Do this in writing and explain fully the reason you are asking the question as this may need to be discussed within the committee. I am not a committee member but I can fully understand why this information is not readily available.
The introductory pages in the front of the printed Triple-M Register 2008 include details of Body Codes, gearbox numbers and Engine numbers so far as we know them.
Copies of the printed Register are normally sold at Silverstone each year and our librarian may still have some in stock.