I too agree with the above - but would like to add that it would be better use the TCie (L series) clutch plate and cover - I believe the clutch cover is the same part. The L series plate is - has - I believe slightly more friction plate area - - ? - (AFAIK) (can anyone confirm ?)
As Nodge says, defo sounds like clutch judder and because of that I would also
meticulously check the rear crank oil seal. IF the bell- housing ONLY has clutch dust then ok, however, if the black crud is not easily removed then consider an oil contamination. This could be either the crank rear seal OR the gearbox input shaft seal.
Clutch judder doesn't occur for no specific reason Terr.
If the rear crank seal is perfect and non leaking, then changing the gearbox for a second hand unit would also (hopefully

) not have a leaking input shaft seal.
Do not attempt to fit an L series (TCie) box - as I believe it will fit ok to the K series - but the ratios are very different. I am sure there are bleeding stacks of K series boxes at dirt cheap prices - along with the K series flywheels !.
The only other thing I would add is do not chose an aftermarket clutch kit ! - go for an OEM part as a minimum spec (cover - plate AND release bearing). The non OEM parts are basically crap (as far as the clutch is concerned) - it is better to do it ONCE and forget it then to go to the hassle of changing the flywheel and box and finding the clutch or release bearing has issues shortly after fitting.
I must confess, I changed my clutch on my TCie about 6 months ago. I went for Genuine parts (but only due to cost here in Portugal) - however I am sure you can get excellent oem parts at a good price - Borg & Beck etc.
Do it once and do it right.

Joe