no such thing as a conversion harness, im sure you could make one if you had a spare speedo that you dont mind breaking.
these are made for chinese bikes, as to which one, who knows, cfmoto probably
anyway, if you dont mind cutting your loom up, you'll have to join the cables, solder and heat shrink style.
its fairly easy, ive done it to a few street fighters over the years.
personally i would cut the plug off your old clocks. (and say 5-10 cm of wire as well to allow for joining)
that way, you can remove the clocks, if you upgrade the front end, or decide to get different clocks late