It sounds like it's at the more debatable end of worthwhile in financial terms. But unless the chassis is rotten or bent they are all physically saveable.
What you do with it should be guided by what you paid for it and what sort of mileage it is. According to the MOT history it's just over 80k which is reasonably small miles for a Z3. So it's a lot more worthwhile putting the money into it than a 120k plus car.
There's nothing on your list that wouldn't be considered a normal issue. But it is quite a long list. I expect you've spent around £500 so far and have another £1,500 to spend. That's assuming you do the work yourself with mostly second-hand parts. I wouldn't call £2,000 silly money to sort an 80k mile 2.2 Sport. But then I would have wanted to pay eg £2k not £4k for it originally.
However you're going to be very lucky to pick up a decent 2.2 Sport for £2k, especially at this time of year. You need to be spending £3-£4k to get a decent car unless you stumble upon a bargain. And even then, unless it's been enthusiast owned there will always be jobs likely to cost into the £100s.
In case of interest I'm not too far off having a 2.2 Sport in Topaz Blue with Lotus White seats for sale. It's done 99k but I've been all over that car checking it and it's a good'un. It will be sold with nothing other than minor cosmetic type jobs to complete. But as I've done all the huffing and puffing to get it like that it will be around £3.5k.