Is there an official M50B25 cylender 3 conspiracy thread somewhere?

I've had a hard hunt to find an un-cracked replacement 2.5 M50 cylender head - every scrap yard I've gone to has tried to sell me a head with a crack in cylender 3...

I've finally located one without a crack but it's a strange one with casting marks I've never seen before... which reminds me I need to post a photo of the one I dont consider to be strange.

Now I need to decide whether to pull piston 3 and replace its rings - I have no idea of the condition of them. The 2.0 head that's on there currently is so buggered it's clanking at tickover but not under power.

While pulling away the cars not smoking much, odd bit of blue smoke, but I think the valve guides have gone on cyl 3 as it's oiling up spark plugs and misfiring at idle.

Trouble is I gots to lift the front of the car to do the pistons with the block still in and I've no garage. Thinking about it I'd have to put it on ramps before I took the head off and that's gonna make getting the head out a a right biatch of a job...

Hmm... to risk it or not to risk (changing the rings), that is the question.