Regrettable Engine strip down !!!! I think

Oh Lord give me strength !!! Just  got to the the stage of head all torqued down, cams fitted. Thought i would check everything with a leak down test. Number 6 inlet valve not shutting correctly. 
Now number 6 inlet valve was brand new old stock ??? this i replaced as the old one was checked in the lathe and found it to be 0.5mm out.
Im in a state of depression with this !!! Also used a genuine Kawasaki head gasket at £200 
So if i now have to disassemble, will this mean another head gasket ? 
 

Are you positive valve clearances are correct?

One of my biggest fears when installing / timing the camshaft on an interference engine AND it also has a valve angle that interferes the inlet and exhaust valve if you're not very careful. The Service Manual doesn't mention it at all. I think what is critical is when installing the camshafts that the cams are in the exact position for timing ( i.e. the timing marks on the camshaft located such that when the cams caps are tightened down, the marks will be in the correct position in relation to the cam cover sealing face) when you start to tighten down the cam caps, otherwise it's possible for the inlet valve and/or the exhaust valve on #6 to bend.

As for the need for a new head gasket- You should probably get lucky and reuse the gasket you have since you haven't run the engine up and put the gasket through a thermocycle. At 200 pounds for a new one, I'd be having it a go. Just be careful and clean off the gasket surfaces and remove as much gasket sealer from the gasket without damaging the fiber of the gasket.
Hope this helps,
KB

Oh yes, even tried it with the thinnest shim !! but using a bore scope from the inlet manifold. When using a powerful torch down the spark plug hole, you can see the valve is not seating.

Regarding head gaskets, OEM $$$ and alternatives.. I now know of 5 peeps who have used 3Bond 1211 successfully on aftermarket, (plain gasket, no goo to compress)..

Copied and pasted..

As to the head gasket sealing, I always used Kawasaki OEM. But they became insanely expensive. I had one old stock which had the water passages silicone sealings peeling off. And there are the aftermarket cheaper option with that completely missing!   

 I bought it, applied, and it created a white line which I left to cure overnight. Next day it was dry with the same consistency as original sealing, solid on the surface of the gasket.  Used this gaskedt with 1211 and have been riding and - absolutely no leaks.

Amazon..

Three days after tightening the cylinder head, about to install the rocker cover, I realized that I had not mounted a section of the timing chain guide. I disassembled the cylinder head again a week after having tightened it to fit the forgotten part, used the same gasket again and had no problem whatsoever.