If the PZeros date from before the car became a garage queen, they'll be at least 5.5 years old by now and in need of changing as well as the fronts.
You're looking at £1.5k for tyres plus Insp2.
Personally I would always refresh the suspension as these cars deserve to be enjoyed on fresh bushes and dampers, so add another £1-2k depending on whether you can do some or all of it yourself.
No VANOS replacement isn't a concern, but no rod bearings is. I'd want to get those done preventatively for peace of mind. £1,300-1,500.
So expect to pay £5-6k on top of purchase price if all of the above needs doing. And that's assuming the brake pipes aren't corroded and discs are in good shape, etc.