The two 0.4 might be a good place to start - step wise tuning is best unless you have a lot of WI tuning experience on a set up. But I do suspect that eventually you will eventually increase the size to two 0.5 or more. Remember you will have both pressure and jet size to adjust your flow rates.
Just a clarification by no means was I suggesting that the hsv is at all lacking as Richard said its performance is on par with most quality fuel injectors - just using one hsv to keep up with 2 injector pulses per revolution is asking too much of it. It should keep up with 1 per revolution fine. Hence the recommendation on the cross cylinder cycle injection.
I will be interested in seeing how the Tec3 tuning goes. If you haven't gotten it yet have you looked at the new hydra system from element tuning at all?
http://www.elementtuning.com/main.htm