Barry, I think Johan has given some good advise. And he should know as he does very well with his car(s).
One thing that is understated is driver training. I thought there wasn't much to learn, having been successful in the past in competition. But I was wrong.
I took a great 2-day BMW school just to learn the limits of my M5. I kept an open mind and with my past experience was able to go very fast.
Then I took the Derek Daly formula course. I never liked the formula cars because they weren't like real sports cars. I improved a lot more at the school. And now I absolutely love formula cars.
I would go with better pads, another degree of negative camber and spend the rest of my time and money going to some good schools. And just go for the fun of it.