Will the Gtx 760 bottleneck a Intel Pentium g3220?

If you need better performance now it would be best to upgrade the GPU to an R9 270. http://www.ncixus.com/products/?usaffiliateid=1000031504&sku=94193&vpn=CGAX-R927614&manufacture=Club3D&promoid=1315

It's at a price where it really isn't worth getting a slower card and it's not worth the added cost to get one that's a little better. You will see a performance increase with this graphics card even with your dual core Pentium but the card won't reach its max potential until you also upgrade your CPU. It's the best deal I could find. upgrading the GPU now is the best move you can make with what's on the market today... But there's another option... You could upgrade your CPU now to a Core i5 and then wait for the GTX 960, 960 ti, or 965 ti. Those GPU's could launch by the end of the month.