To elaborate on the EO/IC method in case you are unfamiliar with it..
On each cylinder, when the Exhaust is begining to open, lash the Intake..
Then, when the Intake is about to close, lash the Exhaust..
This will ensure that the valve being lashed is positively on the heal of it's lobe.
With #1 at TDC and firing stroke, you with be able to then lash #7's Intake and #4's Exhaust and then 8436572 respectively for each firing stroke and valve. (ie: next, rotate to #8 TDC and lash #2 Int & #3 Exh and so on.)
One thing you will most likely see is the lash got tighter when you rotate it to TDC and check again, -indicating that the lifter is now on a slight ramp. It might only be a few thou, but some radical cams will show a lot.
Basically, the TDC method will result in too much lash. Hope this helps.
This may not eliminate your noise, but will at least eliminate one probable.
PS: Check guide plate-pushrod clearance through out valve lift.. As the rocker opens the valve, the clearance generally gets tighter.
Doing a cam dial-in, I once had a set of inaccurately stamped guide plates and it did my head in until I found them out. They would have killed my pushrods in minutes if the engine had have run with them.