This is how I handled it.
I got the heads fully assembled but right away I pulled all the spring gear and stem seals.
Then I felt each stem for slop, and there was none but every valve easily slipped down like it wanted to fall out of the head.
I did a light lap on the valves to verify their 3 angle valve job and they were all fine.
I called it good and replaced the stem seals with a known good quality, as well as all the springs, retainers and locks with Hughes gear and away we went.
The cam I have is only about .512 lift, but I have had this thing to 6k multiple times and no problems at all.
You may not need to take every new head to the machinist but at the very least, looking over the basics is a really good idea.
