NAW set the rockers first
The nut is kind of a locking nut or should be ... put the flat side against the washer and the rounded end up... if you notice you can't thread them on by hand all the way Or you shouldn't be able to ... thats the locking part for the adjustability...
The easyest way I've found to adjust them is ....
rotate the motor by hand and Just as the exhaust push rod starts up adjust the intake of that cylender. rotate the push rod with your fingers just as you feel it stop or feel drag on it.. stop and take another 1/4 to 1/2 a turn. that should be the adjustment ...
Then rotate the motor by hand and just as the intake starts to close from fully open stop and adjust the exhaust valve of that cylender.. the same way.. and repeat for all rockers.

Good luck
tim

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64 International 4dr. truck w/466