Well, I went to view the car today, a 420 GSi Turbo
From the pictures the seller sent me, it looked absolutely mint. A very nice example. Got there and while it was very clean, there were patches of rust along the arches and both front wings were quite bad around the arch.
Started it up and checked under the bonnet. A huge smile filled my face as I saw the turbo and dump valve. Spent 20 minutes checking the car out, under the sills (where mine rusted), the rear ARB mounts, door sills... everything really.
Watched it get upto temperature while revving it every now and then to check for blue smoke. I was very impressed. 102,000 miles and not a whisper of blue smoke.
The guy (really nice chap, very helpful) had told me about the gearbox being noisy, but I didn't expect it to be as bad as it was. It really sounded as though the bearings were on their last legs. The engine was running on its original headgasket, and being an earlier gasket, didn't have the reinforced oil way at the front of the block. Quite sad to see how bad the leak was actually

After I took it for a spin and parked it back up, I left it idling for 5 minutes while I checked other things. There was quite a large collection of oil under the car
However, the performance was ******* stupid! Got in the car, pulled out of the housing area and booted it down a main road. At first it didn't feel that quick, but once it hit 3000rpm, oh my god... into 2nd and holy jesus, I was grinning like a school kid on Christmas day!
Onto another road and pulled out of a junction. Set off normally and once upto 2000rpm, put my foot down. It went like a rocket straight to redline in no time. As I got further down the road, I saw some people walking along the pavement, so had the perfect opportunity to change gear... pssssssssssscccchhhhhhh... the look on their face was awesome as this old grandaddy Rover went past.
So yeah, all in all a very quick, understated, fun to drive car... but this particular example is not for me. Instead, I'm going to get the 220 through its MOT and save up for a mint 420. This one I drove was so much fun, and it was running on the standard BMV so gradually increased the boost. I can imagine one boosting at 12psi all the way through the rev range to be silly quick.