I have a few comments:-
1) Dusts inside a case mostly come through intake fans and only a small portion comes from crevices. So, having a positive pressure case is only a second order preventive measure. Make sure all intake fans have dust filter. For example, the rear top fan does not come with a stock dust filter. If you change it from exhaust to intake, a dust filter is needed.
2) Looking at your 2nd pic, I notice the end result is a hugely pressure positive environment. Basically the PSU takes care of itself. So, the exhausts are just the case rear 140mm fan and the graphics card. Their combined exhaust is like 63+10=73 CFM. However, the combined intake is like 90+90+90+63+47+47=427 CFM. The differential is huge. See pic below:-
3) Such a huge differential might lead to some problem, especially the exhausts are so little.
For example, the GTX560Ti OC2 is a bi-directional exhausting card. Half of its exhaust is from its front (see the red arrow in the pic below). This amount of hot exhaust should get out of the case as quickly as possible. Since the only exhaust is through the case rear 120mm fan, this exhaust should go there. However, there is big air pressure coming down from the case's two top intake 200mm fans. As a result, it is possible this exhaust from the graphics card will stay longer inside the case than it needs to be. Obviously this is not desirable.
4) You need to do some trial-and-error to see which combination of intake fans make the best.
As a start, I suggest:-
(a) top front fan - intake
(b) top rear fan - no use
(c) side panel's two 120mm fans - no use