I don't know what the puzzle car is, but I know for sure, it can't be a FF 2000. Because of far too wide wheels and secondly, as previously mentioned, I am missing the exhaust system protruding on the right side under the engine cover. Of course, it can be a modified FF 2000, but I think, it isn't. The technical regulations of FF 2000 prohibit the usage of a monocoque chassis. The chassis must be a tubular steel one. The use of tubular steel frames in a faster race classes are since the mid-70s rather unusual
Nevertheless here is my next guess:
Is it a 'Sark'?