My chassis is nowhere near standard, fitting the Jag V12 mechanicals has dictated a massive redesign of just about everything

The problem is that the input flange for the diff is offset towards the driver's side so I had to make the tunnel much wider than I originally designed it. Having mocked up a prop I can now see that I can redesign the tunnel to give me the width I need. The front of the base of the seat is the widest point, this is well forward of the flange on the diff so I can make the tunnel at that point just a little wider than the prop shaft, that should give me about 40mm more width. I will look at other seats as well, maybe from things like Corsas and other small cars to see what works best. Mrs is pretty handy with a sewing machine so if I have to mod a stock seat it shouldn't be to big a problem.
Dave.
PS, hope that makes sense, I might take some photos later to illustrate the point.