I heard my Rav say one should be consistent between nusach and tefillin (at least in terms of ksav). But assuming Torah is the Best is correct about Rav Moshe, then it’s OK.
In general, it’s not unusual for gerim and baalei teshuvah to end up with inconsistent minhagim. It’s best to have one consistent set of minhagim, but sometimes exceptions happen, especially during the process of becoming observant.