Just coming from experience that you try to keep the motor power levels at a reasonable level and if you can, you might even initially keep the motor stock. Once you start to start pulling them apart you start to have more issues.
A 250rwkw light weight silvia with fantastic suspension and chassis set up will be a lot quicker then most think and you will be able to keep going around and around all day everyday and also pass most other cars on the track.
Even more important considering the distance you have to travel as no doubt you will try and get a couple of days in at a time, you can do local hill climb events etc if you have them though.