Thanks all for your comments! Putting together the geology has honestly been lots of fun, and a great learning experience. I'm certainly far from an expert in geology (social scientist here!), but even a little bit of research about plate tectonics is rewarding and interesting.
What's... not as much fun has been working on the poles- re-projecting the map in GProjector, drawing the elevation, then re-reprojecting it and tracing the elevation at 600% zoom on the original map. Very tedious and I'm glad to have it over with, even if I suspect I'll do some further tweaking to the elevation before I move on to the actual climate part. Current draft is attached- with the poles completed!
PangarapElevation.jpg