I take it you have the cam sprocket marks (FE and FI) facing away from each other
and the cam lobes facing away from each other also (at approximately ten past ten, looking at a clock face)
If you can just about get the FE mark lined up with the top of the cylinder head OK, but not the FI mark it would suggest to me that the inlet cam is one tooth out.
If the cam chain has stretched that much IMHO both the FE and FI cam sprocket marks would be out, not just the one
Before trying to adjust it, what you need to do is have a close inspection of the cam sprocket and chain to see if it is out enough for a one tooth adjustment to put it right.
This photo shows what one tooth out looks like:-
hope this helps
John