Hey,
thanks for writing the whole - disclaimer etc. thing, as I'm sure you understand you can apply all of that to what I'm about to say.
For me in VCE I achieved 47/50 (it's a different score system) in bio and psych. Bio tends to scale up in Vic whereas psych tends to scale down.
My bio score scaled to 47.66 whereas my psych score scaled to 46.75. (in both cases that's still in the top 1% of the state so it's not a huge jump). How much your score is scaled by depends on how high it is but the highest I can see for those 2 subjects in the year I graduated are 1 point up from scaling (for bio) and 2 points down from scaling (for psych). Some scaled a more than bio or psych but with the exception of languages (which get special scaling) and specialist maths (which benefitted from inter-maths scaling) none were by 10 or more in my year & I'd be surprised if that wasn't more generally true as well. VCE study scores probably won't make too much sense to you given it's a fairly different system but here's a link if you're interested in looking it up for
other subjects and years.
UAC (equivalent of QTAC in NSW) produces a detailed report each year which includes a table showing what the highest ATAR achieved by someone studying each subject was. Here's the
2019 one and you can see that students had 99+ ATARs across a broad range of subjects.
If you had a 80 mark in music be scaled down to 50 or 60 I would be very surprised. Obviously I can't guarantee anything about what the specific numbers will be etc. as you've said, but in general I'd say you have less cause to be anxious about the impacts of scaling than you think.
I hope this puts you at ease a bit and please feel free to follow up if there's anything you'd like clarified here