Hey there man, so I did an S340 Build which was uh...interesting. It turned out like this: https://www.reddit.com/r/watercooling/comments/4f6n10/first_loop_didnt_turn_out_too_shabby_hardline_s340/?

So, obviously that is not great right? I mean, the temps were great and all, but not a show piece if ya get what I mean. The main problem I ran into was with that exact pump/res combo...it ended up being too wide to fit between the rad (280, 30mm) and the GPU (980 Ti Classified). I would really urge you to check out a new case because it makes things look so much better than in the S340.

I re did my build completely in a Fractal Design S and this is what it turned out like (just a crappy quality picture from my phone, but much, much better obviously) http://imgur.com/fQa3hmp

So, ya know man...its up to you, I think soft tubing will be much easier in the S340 than hardline, but if you want to use the S340, just make sure everything fits, that was my mistake, and I worked with what I could. So ya know, just make sure it all fits, thats the main thing. Also, just a heads up, if you have the 120 in the back, the front panel won't actually close properly (This occurred with me and another who has built in the S340) the 120 in the back causes the Front panel to not latch properly.