Hey Jamie. I race up at Harewood and Ruapuna
I think there are probably a few other Kiwi's mulling around these forums too.
For the body shell you usually need to use an NZRCA approved one, but not sure of your rules down there. Most people up here use the Protoform Mazda 6 or Dodge Stratos.
The ESC is a huge one. TO a point, better ESC's will have lower internal resistance and so won't heat up as much and provide more power to get through, but with the 1300's, that isn't such an issue. We will probably go to Lipo next year i'm guessing, so the ESC will play a bigger part.
I'd try and get an ESC with Lipo cut-off to future proof yourself, or else get a cheaper one and then upgrade later is necessary. I used a Tekin G-11 and it was great (but very old). Other brushed ESC's like the Tekin FX and Novak GTX or GTS-Pro are also fine for silver can racing.
Servo's in stock don't need to be that fast. You won't notice the difference between a 0.07 or a 0.10 transit time with the speed they go. Hell, I used a standard Futaba 3003 in my 13.5 for a while! Just about any Futaba, JR, Acoms, etc will work.
Just my opinions, others may try and convince you to spend $1000's