A Reader Question about Ad Orientem in the Modern Liturgy

A reader sent in this question a few weeks ago. I gave them my thoughts, but I thought there would be merit in opening up the question to others; in particular, priests.

During our meeting today we were discussing some questions that are beginning to arise as more and more priests in our diocese are beginning to implement changes consistent with the reform of the reform, as it were.

Specifically, we were discussing the questions of one pastor who would like to begin celebrating the Novus Ordo occasionally ad Orientem. The question regards the orientation of the celebrant for the Collect. Both the study text of the English Translation of the Order of the Mass and the GIRM indicate that the Collect is said at the chair. In this particular sanctuary – and presumably in many other sanctuaries designed for the ordinary form – the chair is fixed in a position facing the people and, consequently, facing away from the altar. Therefore the question becomes, when celebrating the ordinary form ad Orientem, should the celebrant pray the Collect facing the people (as is typical) or would he turn at that point towards the altar?

I would be very interested to know how this question may have been addressed in other places where the practice of celebrating ad Orientem has been reintroduced and in hearing your opinion on the matter.