I remember the valve lash procedure for cold lashing (aka not running, assembling, on stand, etc) standard small blocks with the 18436572 firing order, never had an issue like this, once you get good at knowing how much preload you should feel on the pushrod you can count on it working everytime.
Bring the engine to top dead center(TDC) for cylinder #1 on compression stroke. Both of the timming marks should be at the 12:00 position or, the timming mark at 0 degrees]
, and the lifters for #1 should both be at the bottom of thier travel in the lifter bores.
Now the engine is in the #1 firing position.
Adjust the intake valves on cyl #s 1,2,5,and 7
Adjust the exhaust
valves on cyl #s 1,3,4,and 8
Then rotate the engine 360 degrees so the timing marks are at 12:00 again, or the timming mark is back at zero degrees.
now the engine is in the #6 firing position.
Adjust the Intake valves on cyl #s 3,4,6, and 8
Adjust the exhaust valves on cyl #s 2,5,6, and 7.
This procedure only works on small blocks with a conventional firing order of 18436572.
it's as simple as that, if you don't know how to adjust valves by the pushrod feel x degree turn method let me know.