I just did some testing, and TC is definitely 390 initial + 320 dot = 710 total. 15 minutes of hitting dummy with F3 and thunders.
Highest non-crit F3 = 3269
Highest non-crit TC = 2939
432/390 = 1.108~
3269/2939 = 1.112~
E: It appears there is a bug with ACT and Thunder ticks. No matter what level of Thunder you use -- whether it's a TC proc or not -- ACT will only show and calculate damage for six ticks.
