Raise playback pitch by 6 semitones

I am transcribing a pop song for keyboard. Pitch details:

Sounding key of original recording: Eb minor
Sounding key of my synth (pitch-adjusted) for our upcoming performance: Eb minor
Written/played key of the score I am creating: A minor

Thus, I will create a part that is read and PLAYED (A minor), but SOUNDS a tritone higher on my synth (Eb minor). And as I transcribe by ear, listening to the original pop recording in Eb minor, I wish to PLAY Musescore in A minor, but HEAR it in Eb minor.

Here are the problems I am having:

1. Adjusting transposition in Stave/Part properties transposes the written score. (I explicitly wish to change the playback only, not the written key)

2. Adjusting playback pitch in Synthesizer/Tuning: This tops out at 600 Hz which, I believe, is a perfect 5th; I need an extra half step.

Of course, there are probably workarounds. But is there a way to achieve what I am attempting without compromise?

Thanks,
Lance