78' sohc 750

picked up this last week and upon my prelim check I find some oil/grease build up as seen in 2nd and 3rd pics. Initially thought head gasket gone but compression is 120 psi x 4 cylinders and same staining in the spark plug cavities. Any ideas of its origin?

/Users/nicholewagner/Pictures/iPhoto Library/Originals/2015/Roll 1173/PB090021.JPG


/Users/nicholewagner/Pictures/iPhoto Library/Originals/2015/Roll 1183/PB100012.JPG

/Users/nicholewagner/Pictures/iPhoto Library/Originals/2015/Roll 1183/PB100015.JPG

Looks like the valve adjustment cap on #3 exhaust has been leaking. I would start by replacing that o-ring because that's the easiest. If that's not the problem, then it has to be a leaky valve cover o-ring.

thanks for the reply! Wow what a difference a second set of eyes on something can be. I've been looking at that for ever and didn't see it.