Hold on thar… There is also a limit to the number of outputs that can be sourcing or sinking current for the chip as well. Not sure what it is. 
Well, the SO-packaged variant is rated at 500mW of dissipation at the absolute max. Assuming we run the device at 5V, the device should draw no more then 100mA. Of course, this is the absolute max, so you don’t want to go anywhere near there. For me, I would further derate the power dissipation to be on the safe side, and go no further then 80mA of usage. The quiescent and the current that the device itself is drawing (under no load) is negligible since it’s in the uA.
80mA divided by 8 (since it’s chip is driving 8 signals/servos) would be about 10mA. I would further derate the usage on it to be even safer and dissipate no more then 5mA per pin, assuming a condition that all 8 pins were lighting up the LED.
You can then do your voltage drop/ohms law to calculate the the series resistance required to achieve no more then 5mA draw for the LED…
In my experience, 5mA is PLENTY for the type of LED we use in these bots…
The spec sheet seems to say 70ma is the max limit on the vcc and ground pin.
I seam to recall setting up the ultrabright T1 LED’s for 20mA which is the maximum. They will work at 5mA but would be considerably dimmer. All you really need to do is make sure you only connect two or three LED’s to each bank, (595 chip.) Then you can have up to 12 LED’s driven at max brightness and they can all be on at once.
The worst case current rating was assuming that every single port off the SSC-32 was used as an LED driver, with no servos.
This is not really a realistic case but was just a math game to see what could it possibly do under worst case scenario.
Since each pin can source/sink about 35mA, spreading out the LEDs to different banks would be the best case for super-brites…
That reminds me, I still gotta do this mod… My CH3-R has been neglected lately due to my busy personal life… Oh my hexy, how I miss thee… 
I was gonna put the dual color leds in mine …then when its dow its on color and up would be the other color… 8) .blue and red…
I think that would look neat…also the have tri color leds that change while on…really nice effect… 8) 8)
someone have a pic of the mod for leds and the subrutine too?
tkx