a 970 for 1440p is kind of cutting it. You won't be able to max a lot of games at that kind of resolution. Though going from what i'm assuming you have a 60hz to a 144hz is also a big step and with a single 970 you can't really take advantage of that resolution.
I say look into upgrading to a better gpu, personally dual gpu's aren't worth the hassle. Then i'd think about getting 144hz or 1440p.