Moving from a teaching position to an administrative position is not a promotion into a senior position. It is a demotion albeit given more budgetary responsibility.
The core business of any education institute is to .... EDUCATE. Repeat after me three times. The core business of any education institute is to educate. The core business of any education institute is to educate. The core business of any education institute is to educate. Administrators are there to support and serve the teachers doing their job. Administrators are here to ensure that nothing will hinder the work of the teachers who are doing the CORE business of any education institute.
A promotion from a teaching position is to the "head" teacher position where the responsibility is to provide leadership, demonstrate innovation and creativity to the fellow teachers, excite and inspire the students, cultivate an effective and lively learning environment, etc. - in short STRENGTHEN the core competence of the education institute.
I know some principals who still teach a lesson or two, "to keep in touch with the students". Unfortunately, I also know a lot of them only do that half-heartedly. They took "easy" or unimportant lessons citing too busy in administrative duties to take on full responsibility of a course! My suggestion, don't put the car in front of the horse! Administrative duties can be shared. Leadership, innovation and strengthening the core competence of the education institution is the FULL-TIME job!