On top of one of the cylinder head pedastals there is what the service manual calls a "rocker shaft lock plug."
That has to be removed before the rocker shaft, rocker arms, springs can be removed.
Your heads and engine are sludged up from what i have been reading in your other postings.
That's why you can't see the lock plug, with the sludge on the heads.
Not to be a critic of your mechanical skills, but a factory maintenance manual would have done wonders for you in your undertaking, what your attempting to do.