None with any decent engines unfortunately, been after one for ages, got a post on there so i thought i would try here too, the ones ive seen on there have been in trouble, i.e. Head gasket etc
Always a gamble on the used market have you tried any merc breakers then you could possibly get a 3 month warranty on it so if its no good send it back??
Just buy a whole car for £500 and use its engine. I would change the head gasket if it's not been done already, purely as a preventative measure as they all tend to go at about 110k miles.
And get a later duplex chain timing gear engine if possible which came in around 89 irrc. As has been said there's hardly any M102 engines haven't had the head gasket done but the bottom end of these motors is strong and good for 200K if fed good oil on a regular basis. You can feel timing chain wear through the oil filler cap [ engine stopped of course] and CHG problems revealed by mayo under the filler cap or on the dipstick or misfire on cold start up or oily deposits in the radiator header tank.