Is it permissible to pronounce the letter Qaf in the verse, "Say, He is Allah, [the] One," as a Hijazi Qaf, while being able to pronounce it as a classical Qaf?

Every letter of the alphabet has a point of articulation (makhraj) and characteristics (sifat) that must not be altered. The letter Qaf, for example, is articulated from the deepest part of the tongue with what is above it from the palate. Its characteristics are: Jahr (audibility), Shiddah (strength/stop), Isti'la' (elevation), Infitah (openness), Ismat (prevented from quick utterance), and Qalqalah (vibration/echo). Any change to the makhraj or sifat of the Qaf is considered an alteration of it to another letter or a different sound, which is prohibited in the Quran for one who is capable of pronouncing it eloquently. Some scholars have even gone so far as to declare the one who does so an apostate. Therefore, whoever pronounces the Qaf in the Quran in an ineloquent manner while being capable of pronouncing it eloquently has committed a forbidden act and must repent.