Circuit breaker for trunk-mounted battery?

[jlwdvm]

I have my Optima battery mounted in the trunk of my 69 Firebird LS3 track/street car with the battery cable running up the center of the inside of the car to a master on/off switch mounted in the dash, then to a firewall pass-through terminal, and then on to the starter. I have a on/off positive terminal end mounted to the battery. I just saw in another build thread that a guy used a 200amp manual breaker mounted about 18" from the battery. It seems like this would be a good way to protect against any shorts in my long battery cable. Thoughts from the electrical gurus?