Peter, having done several sprints and tracks days when I owned a TVR Griffith the answer to can the setup be improved is very likely to be yes. I would expect that Tarka is currently set up for general road going use and to maximise tyre wear, as most cars are.
The Grif initially was ok but I reset front and rear suspension adding 0.5 degree of negative camber all round and I increased the tow in slightly to give quicker and more responsive turn in. The rear end got a stronger anti-roll bar. These changes made a huge difference, the car was more stable and I could corner significantly quicker, much to the annoyance of the chaps in 5l Grifs, mine being 4l. The downside was uneven and quicker tyre wear, plus a slightly harsher ride, but if your doing track days your probably not worried about tyre wear.
The MR2 hill climb car, which has completely adjustable suspension like a race car, I set up in a similar way, but it was also lowered 3/4 inch and I fitted racec polypropylene bushes all round. The result was a big go kart. Pretty twitchy at first, but once you got used to it and with hot tyres it flew round corners and was a lot of fun.
So from my experience a tight tuned setup that pushes the boundaries of a road going set up a bit further should give improvements on handling for track use.
