Okay, so thread concurrency:
You should try 10240 (assuming your 290 has 2560 stream processors, this is 4x the number of sp), and compare the resulting hash rate to your current performance. Personally, I would drop the g and the w and compare the results, or you can leave them and compare... If you drop them, by setting thread_concurrency cgminer should pick optimal value for those settings itself. If you set G statically, that changes the optimal value for thread_concurrency however and it will likely yield worse performance from what I'm reading. Similar for w, let cgminer decide based on your setting for thread_concurrency, which is optimized to fit the number of stream processors on your card.
This is only based on reading, interested to hear your feedback on if it helps or hurts tour hashrate.