From the 2005-2006 NFHS Wrestling Case Book and Manual (pages 44 and 45):

7.1.5 Situation B:
Wrestler A applies the guillotine with a headlock and then turns Wrestler B towards the back.

Ruling: This is an illegal headlock since it is not permissible to lock around the head without an arm in the guillotine until near fall criteria has been met. In this situation the headlock is applied prior to turning the opponent and is therefore illegal.

7.1.5 Situation G:
Is it permissible to lock your hands around your opponent's head in the guillotine without encircling an arm above the elbow?

Ruling: This would be legal in the guillotine after near fall criteria has been met. The hands may remain locked as long as the wrestler is able to hold the opponent in near fall criteria. When the defensive wrestler is able to come out of criteria, that is either letting both shoulders off the mat in excess of of four inches or when one shoulder is on the mat, the other shoulder is in excess of 45 degrees off the mat, then the locked hands must be released. The referee may need to notify the wrestler when they reach this position so that it can be corrected without stopping the match. This would be a situation where the illegal hold would be caused by the defensive wrestler and, therefore, the offensive wrestler must be given an opportunity to remedy the situation.