Last year 116/140 would get you an A+, so probably high 30 / low 40. At the high end of the 40s, you need to be dropping very few marks, probably around 2-4 in my opinion
Some years though loosing 10 marks could get people 48+

but it varies, I reckon you should aim for 65/65 multi choice or close to it, then loose less then 3 marks on short answer. I say this because section C is really unpredictable and you can loose upwards of 5 marks for even an above average repsonse. Last year no one got 10/10. The average is around 4/15

although it may be 4/10 just for the big 10 marker.
So yeah just loose minimal marks in section 1+2 and give section C your best shot. Psych seems to be a subject where you can loose a fair amount of marks but 1 mark can be the difference between 48 and 47 because it is still very comptetive,