Sounds to me like the big ends went and somebody had a look and decided against it.
On my 2.2TC the big ends went after about 700 miles of ownership, very little notice other than low oil pressure at idle, next thing it's banging like... well I'm sure John could come up with something to describe that.
I dropped the sump, and there was about 1/4 inch of play in the at least one of the big ends, bearing had pretty much destroyed itself.
I binned that engine and just dropped another in.
So they can turn from perfectly good runners to scrap very quickly, I suspect somebody stitched somebody up along the way. Makes you wonder about these cars you see on ebay "Doesn't run but it's probably just the coil..." Yeah right !
Shame to see you selling the car, but you can only take so much, and I know things are very tight for a lot of people at the moment.