Which Dana 60 Differential and axles ?

Getting ready to have my Dana 60 narrowed , I have a 4.10 track-loc in it now with 30 spline axles that I will toss and have new axles made .
My question is ...... should I throw even more money into it and get another Differential , such as a TrueTrac or a Detroit Locker ?
Are the 30 spline axles strong enough with my stock track-loc ?

My car is an all steel 68 Barracuda fastback , 505 cubed RB , 727 tranny .
I haven't picked out my converter yet .
Rough guess is 600-630 HP with the CNC'ed stealth heads .
99% street driven with a few passes at the track a year , and maybe some on the street also :)
I will have drag radials on the car as soon as I get it mini-tubbed . Which is being done now .
Should I stay with 30 spline ? Or jump to 35 spline which then I have to get another differential .
And which differential if I do change ?
I did get the wilwood rear disc brakes for the car .
I was hoping the factory dana stuff would hold up to my heavy right foot .

Donnie
:burnout: