Steve, I have the same rims all round - 17". I am running lower profile tyres on the front though: 195/45 with 195/55 on the back. The wheel size was due to the fact that finding 16" wheels with 5 bolts proved to be impossible. The only problem I currently have is the wheels hitting the headlights - you get a nice smell when that happens :s Will have to think of some way to modify it....
I lowered the tyre pressure as suggested - initially to 18psi at the front and 20psi at the back. It definately had a positive effect along with tightening up the steering - I haven't managed to get it to wobble significantly yet.
Given I have just fitted slightly stiffer springs to the back end 350/8 I haven't taken the car in for the 4-wheel alignment yet as I'm waiting for the springs to settle in. Hopefully when that is sorted the handling with improve a bit more - half the fun is just playing with it I guess
I shall go and take some pictures of the harnesses and see if I can find out how to upload them.