I think the rear end setup will be great with the leafs and the panhard bar. I have seen some of the British Falcons in vintage, and the rear suspension/leaf spring setups are very similar you yours, but unlike anything else I have seen for sale in the US.
I will certainly give you feedback. The panhard bar is a tight fit back there between the fuel cell and the diff, but I think it will be the trick to having some adjustability at the track.
Most of my track experience is 6+ years of Lemons and Chump car, where we have actually fabricated suspension parts and put together our own leaf springs. The best part of that racing is literally hundreds of hours of seat time, and I think I have a good feel for handling at the track, albeit with low horsepower RWD cars. This will be my first experience with high horsepower and bias ply RWD in a sprint race format.
I know I am working on a completely different level with great quality suspension parts from C.A., Opentracker, and Maier and look forward to getting to the track in Feb or March. By next summer I hope to field a car in SVRA/VDCA/HSR here in the southeast.