OK let’s first correct that to a one “L” Traveler.
Yes both have been done before in the UK, check out
AAN Search Results | Airworthiness | Safety Regulation
The 1975 Traveler’s are basically the same as the earlier models, but with the Cheetah engine cowlings, induction system and main undercarriage clean up fairings. That all sounds straight forward as long as you have ready access to the Cheetah donor parts.
As for the cowling here is just a quick list of what I can think of you will need from the Cheetah. Top and bottom cowlings, Nose leg boot and retainer, nose bowl, all engine baffles, airbox, airbox to carb duct and ideally the engine mount although the one done under the above AAN modified the cowl centre hinge to clear the top of the original engine mount.
If you are going to do the main leg fairing clean-up be aware that the fuel sump covers of the Cheetah will fowl the sump drains unless you reposition the sumps or modify the sump fairings as was done on G-BAOV.
Now for the interesting bit, fitting the larger tailplane. Because of the completely different way in which the Cheetah’s tailplane is attached, by far the easiest way is to replace the complete back end of the fuselage beyond the honeycomb cockpit section and it looks like this.
The added advantages of doing it this way is that if you have a pre 1974 Traveler you also gain a baggage door and longer rear windows.
To accomplish this, it is all covered in the maintenance manual at
http://urlzr.mp/57