I still have two old 8" woofers by Harbeth which I bought in the late 1980s. They are marked LF8MkIII and bear a golden star (probably for matching?).
Now I suspect these are the drivers which were sold in Germany without consent of Harbeth (you said something about those in the old forum - yes, they were advertised as genuine Harbeth drivers) - but they still look very similar to those used in the H.L. Monitor Mk III (I hope these are real Harbeths at least).
Do you still have the cabinet (and port) dimensions and the schematics for the crossover? I know that there's much more to speaker design than putting the parts into some home-made box, but as I still have the drivers here I hope it will make a very decent low-budget speaker at least - even if it won't equal the quality of your current products.
Thank you very much,
with kind regards,