I would recommend skimming the head (10-20 thou max) or replacing it. Most likely is either a warped head or cracked cylinder head (probably around cylinder 4)

@ Glennyboy: the basic bottom end is the same between the 2.0 8V and 16V engines as long as the engine came from a Scorpio, not a Galaxy. The problem is the top end.

The 2.3 though is different due to the balancer shafts fitted. The block has a bit cut out which needs a metal insert making and fitting or else the front lower cover does not seal.