Vacuum leak through valve cover possible?

[Pablo M]

So many of you know my trials and tribulations in getting my 1972 2002tii running. I seem nearly there but still fighting suspected vacuum leaks as my idle still surges and is too high (~2000rpm ish). While researching DIY smoke testers one discovered they had a vacuum leak at the oil filler (newer BMW). 
 

Got me thinking, because when I put my valve cover back on I did take note it was warped compare to the head. It did not sit flat, with possibly 3-5mm of wobble  between corners. I just figured the nuts would solve that and they went on in proper sequence, torqued down. 
 

Could this be a be a contributing factor? I guess now more than ever I need to sort out a smoke tester…

[Son of Marty]

No, the m10 engine is not effected by vacuum leaks to the crank case. 

[dlacey]

....The only way this might happen would be if the crankcase breather connection on the cam cover was connected to the plenum instead of the air cleaner.... Seems unlikely.