Did not have valve job done because it did not need one, evidence of recent head work so had machine shop disassemble heads and check guides, (excellent), plus measure springs, etc. I neglected to have him clean-up the combustion chambers, (my oversight), they were not terribly bad w/ carbon but it became an issue once precise measurements were needed re: piston/valve/head clearance.
Sooooo....., took them apart and cleaned them + lapped valves. The last pic in previous post is one clean/one dirty valve. It turned-out that the valve springs measure perfect but they were shimmed all wrong in terms of installed spring height. There are a couple of (slightly) varying specs on this, we went with stock 912 spec since they are 912 heads and cam. The original 356 spec was 1 mm less on exhaust valves. At any rate, the last guy had them off by 2-3 mm and not even all the same. That's a ton off. My guy did not measure them, he assumed that they were alright and simply re-assembled heads as they were given to him. Good thing I had to take them apart!
The valve seal is excellent on all valves, other than dirt/carbon, they were like freshly ground. Dirty vs. clean CCs: (I used a soft wire "cup" on drill that put a chrome-like finish on them):
Lapping valves:
Measuring installed spring height:
