What's the ballpark figure for such a restoration (many pieces of string come to mind), and what would it be worth afterwards ?
The cost of restoration is dependent upon who is doing the work. If you put it to a dealer/restorer then you you never going to break even , let alone show a profit. If you just want a workmanlike finish, rather than show condition then it can be done more cheaply but I imagine that even with this in mind it will still be around £10k of parts alone (esp as MMC parts are increasing at an almost exponential rate for many items), plus a full respray (say £5k) and possible re-trim (say 3.5k) and that assumes that the engine.box/axle are all OK. The body tub looks good , it is possible this was purchased from MMC already which is a good start.
You might expect £20k at the end of it. possibly a little more as it is a 4 seater?