Oops sorry didn't see you wanted general surgery or plastics. I know in the US it's really hard to get into general surgery and virtually impossible for an IMG (including US-IMG) to get into plastics.
General surgery is very hard for an IMG but if you work super hard and do awesome on the USMLEs and get US Clinical Experience and solid LORs and so on then it's "possible." After doing a general surgery residency, you could try to apply to plastic surgery. But again no guarantees as if I'm not mistaken general surgery applying to plastic surgery is one of the more competitive applications, but best to ask on the general surgery forums (Winged Scapula?) about this.
It's really hard, and I agree with Medstart108, if you're set on general surgery in North America, best to go to North America if at all possible. Also, we don't know how things will change in a couple of years with more med schools in the US graduating more med students and spots filling up etc.
Just know if you come to either Sydney or Melbourne, there's a strong chance you may not be able to match into general surgery or any other type of surgery. Of course work your hardest from day 1 and hope it works out, but just don't count on it in case it doesn't (and general surgery would be your best bet). If you're okay with that, it's a great experience to study med in Australia.