It's started to behave itself now... it only blows smoke if you really rev it, and even then it doesn't blow much. The only thing I've done is take the PCV valve out and top up the oil, so I dunno. I'm yet to do a compression test, but I think I'm safe in saying that the compression is good, I think I'll just replace the guides and valve seals.
It's a bit of a mystery
buuuut it's a Jeep so I'm sure it'll be fine
Edit: It's amazing what a bit of fresh air and exercise does for a motor... 3 kilometres a day for 3 days and the smoke is GONE. Works for me!