I don't know which parts cross over. If I were you (and I'm not), I would just buy parts as I break them. I made a good sized order to A main and got A arms and stuff you usually break. Cost like $150.
As far as electronics ? That's up to you. My buddy has been running at the front for the last 2 years with a Hobby King 1900kv motor and ESC. Cheap motors and seems pretty reliable. I have had good luck with Tekin stuff.

PS. I have no idea what electronics you already have. You are looking for the fastest motors on the market and will need a 4 cell battery to power it. These buggies are nutso fast. If you are new to the hobby, you might want to start with something a bit more drivable like a short course before your first race ends up with your nice new car in pieces because you can't handle it. Remember it's not about speed, its control.