Black smoke excess fuel,blue smoke rings, white smoke unburnt diesel

The only problem with reconditioners "Guestimates" is they dont really know how stuffed the motor is till its pulled down
IF the head is perhaps cracked beyond repair (like my ol GU 2.8) there goes 2K straight away

Id either get a 2nd opinion on the motors condition,then assess the situation
Live with it, drive it in the ground
Or look for a good running condition 2nd hand 2.8 T diesel
OR , even buy a complete running car