please don't overfill as you'll blow oil seals due to the pressure build up.
to replace the camshaft seal, you only need to take off the cam cover and you can do it without removing the engine or anything daft like that. get the manual that's posted atthe top of this section as it gives the order which you undo and tighten the bolts to stop the cam cover warping.
tank off, top mount off, tacho cable off, cam cover off.... sorted!!
so much for "professionally" rebuilt engine!!
drewps