With reference to your clutch judder problem, there used to be a problem on some cars (notably Fords) called "clutch thrash vibration"
It first surfaced (at least on MY horizon) talking to old hands when I was a just a new apprentice and the earliest victims were MKI Consuls and Zephyrs. It turned up again in the 70s with the MKI and II Granada, and was initially blamed on prop alignment (hence the sensitivity I mentioned above) Eventually, an uprated clutch driven plate was produced by Ford which cured it completely.
It occurs to me that nearly ALL available clutches these days will be copies made with different materials (ie NOT asbestos!) so this could be a factor! I also remember that, back in the day, those of us "in the know" would go out of our way to get a Laycock made clutch for both Sprints and any "big 6" saloon Triumph we had to put a clutch in. The Laycock was quite a lot more expensive, but well worth it, in terms of longevity and smoothness of operation. I have no idea how to get hold of a Laycock clutch nowadays, but perhaps there IS a better alternative driven plate around somewhere waiting to be discovered, or from one of the aftermarket tuning companies like Larkspeed (who I know do compo clutches for Sprints, i've fitted one, not to my own car, and drove it on the RBRR, seems OK so far, but only done about 3k miles)
2 door '73 Toledo with Vauxhall Carlton 2.0 8v engine OWF 797M (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine EGP 247T (The Dolomega)
'91 Cavalier 2ltr 8v auto
'95 Cavalier 2ltr 16v auto
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Apprentice served Triumph Specialist for 45 years and home of Maverick Triumph.PM for more info or quotes.