240sx valve lift

I was wondering if anyone knew what the actual valve lift numbers are for a KA24E. I've looked through the FSM and it shows rocker numbers, but nothing for the actual valves. Is there a place to find this information?
Also, i've been unable to find replacement exhaust valve springs. Are we required to use OEM valve springs, or are equivilent aftermarket acceptable? If so, any recommendations.
Any help would be greatly appreciated.

Thanks Brandon
ITA 240sx #16