I am looking for a machine shop to pressure test and machine the cylinder heads on my Disco. Does anyone know a shop, or have one they would recommend.

 

Usually there is one or two good ones in a modest town. Near me Saul's Cylinder head does good work, about $125 per head ( he does the valve job and uses parts from your HG kit).

You can eat off the floor in that machine shop. That may be a sign of attention to detail, or just too much spare time. Rover heads are simple things and not much of a challenge for a shop.