Ordering a 9"...what to get?

[jlwdvm]

I want to get a rear end lined up for my 69 Firebird Trans Am inspired clone. The car is already mini tubbed, 6-point roll bar, Ride Tech stage 2 front and rear with coil overs and muscle bars, DSE sub frame connectors with stock front sub frame, etc. I am looking at a crate 525hp LS3 from SDP and a 5/6 speed. The car will see road and a lot of track time (road course mainly). I have been looking at ordering a 9", but am unsure on width, gearing, etc. The car I track now is a 2013 Boss 302 and on the 3.6 mile course I rarely get out of 4th gear. Thoughts?