Sounds good to me, also.
Be sure to check for the correct valve train geometry. Your builder will know about this, but there is a chance that stock length pushrods may not give you the right geometry. This is because of the valve job being done, the block and heads having been decked, the chance of a different thickness head gasket from stock, manufacturing tolerances, the type of rocker arms you use- ALL have an effect on what the right length p-rod will be needed.
Also, the guide plates need to be checked to be sure they're aligning the p-rods the way they're supposed to and not binding.
The guide slot in the head will need to be opened up some (if it hasn't been already) so the guide plates are doing the p-rod guiding and not BOTH the head's slot AND the guide plate- this doesn't work and will put the p-rod in a bind if both
are trying to guide it.
Your heads are marked January, 1966. There was a change made during the year that went from stud mounted rockers guided by close tolerance head slots like I mentioned above, to self-aligning rockers. From HERE
From 1962 until May 2, 1966, all 221/ 260/289 engines had pushrod guides cast in the cylinder head. Beginning May 2, 1966, Ford went to a rail-style rocker arm where the rocker is centered at the valve.
is more on the heads and how the p-rod is guided.