G'Day James,
You have a similar setup to me (for the purposes of drift aligning). Th simple rules I use are:
For altitude:
If the star is in the East, adjust opposite the drift.
If the star is in the
West, adjust
With the drift.
For azimuth:
Use the right hand rule (looking at palm of RH with thumb at right angles to fingers):
If the star drifts in the direction of your thumb, adjust star in the direction of your fingers.
This will work in any SCT or reflector with an
odd number of reflections. e.g. a refractor with a diagonal, or an SCT with a diagonal.
Al.