I'm not so sure on engineering now that I look at it unfortunately, because of my lack of maths skills!
Just gonna say that you shouldn't let the math you do in VCE completely define your mathematical capabilities in general.
I got 35 in methods, which isn't amazing, but not bad either. For every methods SAC, I was only just passing and I even still remember getting 42% on the highest contributing methods SAC.
Just remember that math in uni and math in high school are structured differently (imo). VCE math intends to seperate students to create a rank whereas uni math aims to test you on what you know.
As long as you put the effort in, you can do well. Last semester, I did Foundation Math (spesh equivalent) in engineering and throughout the semester,the effort that I put into this unit was no where near the amount of effort I put into methods, which I worked my ass off for. In the end, I got a distinction, which I over the moon with haha