It's definitely possible if not a certainty if your willing to work hard enough. (Being on this forum implies that you are).
The higher you score in a subject the less it will be vunerable to scaling down.
Lets use a subject that you're doing as an example.
Food Tech:
At 30 it scales down to 23
At 35 it scales down to 28
At 40 it scales down to 34
At 45 it scales down to 41
On the flipside though, once you hit scores like 46,47,48,49 it scales down to 43.6, 45.2,46.8,48.4 or thereabouts. (That was using 2013 scaled scores which gives you the correct scaled score, Atarcalc doesn't have the 2014 version yet).
And finally once you hit 50, your score doesn't move.
You can definitely achieve the Atar that you want with subjects that don't scale up.
Good Luck OP and I definitely commend you for not buying into "I have to do Spesh, Lote, Chem, Physics etc only because they scale up ridiculously".