An upgraded CPU will probably still be in high usage when streaming. Especially in 60 FPS, there may not really be a CPU that powerful that handle high quality broadcasting like it is just running a web browser. If there were such processors, I do not think that should be a priority compared to your graphics card, which may need an upgrade. I'm using an Intel I5-4670k and can easily record in 60 fps in 1080p (my worries are NOT about performance, but more about the video itself such as video file size and compression quality).
Your current graphics card is a Nvidia GT 730, which is in need of a upgrade since the I5-4690k seems to be a refresh of my processor that can overclock better due to a material change (if I'm thinking of the right CPU). A CPU higher than that may be bottlenecked by your GT 730 if you play games other than Minecraft (which I do). You can consider overclocking your I5 if you are under the right conditions.
I'd go for the graphics card and check to see if the power supply works (I have a SeaSonic 650 Watt Bronze+ with an AMD Radeon 7970)