My HSC chem mark was lower than that and I still did 1031/1041 and got decent marks, but it's up to you. You can move down to 1011 if you don't like it, but I don't know how easy it is to move up to 1031.
And on the topic of psychology, I really liked it (but then again I'm doing neuroscience). The written assessments can be kinda annoying though, but the final is pretty good. If you're contemplating psychology, psych A is more artsy stuff (like social psychology, health psychology, developmental psychology, etc) but psych B is more biology stuff (neurobiology, memory and cognition, animal learning etc). So keep that in mind.