Dont know if thats still in the normal range or not, but,  here is
Comprehensive Technical Info. on the LS2 which includes a Cooling
Section and Trans. Section (Helms is the Source)  :

Address:http://www.ls2.com/forums/showthread.php?s=&threadid=405808

If you dont find it in the above, then maybe a quick phone call to your
Dealerships Service Dept. might give you the info.   I assume youve
power washed the Trans. Cooler and Radiator (?).  Ive always read
material that said Trans Fluid should not exceed 210 f. but i dont know
if it applies to the C6 .

Let us know the outcome.