I couldn't work out the engine & exhaust, other than it's not the same as mine !
The registration letter (K) puts it the same as mine, 71-72, when the TC came out here and the bodywork looks TC style because apart from the rear deck cut-aways the rear lid and small front spoiler look correct. All are possible updates on an S2 of course but a lot of work just to make the car look something it's not.
The engine fools me. I've no guesses other than it's quite expensive over here to rebuild a TC properly, especially if the head is damaged. So one alternative might be to replace with something cheaper ? The description & pictures don't do it credit but at £8k (or less with haggling) for something that looks like it might move under it's own steam, that's probably cheap for the UK.