Sounds like your decision is whether to buy a 1080 instead of the 1070 to test with your existing system.
Due to each motherboard bios using slightly different wording, for overclocking your 3570K the best bet is to google forum thread guides tailored to overclocking your exact motherboard back 5 years ago when people were doing them for the 2500-3770.
There is only 1 voltage you need to change for a small to medium overclock.
In the last 2 years I've spent on a new monitor, 120gb->500GB SSD, the 1070 last year, £300-400 on peripherals (Wheel, pedals, Hotas Joystick).
A CPU upgrade wasn't really considered when I decided to stay at 60hz. I didn't feel it would give anywhere near the experience boost as the above stuff. I appreciate that for twitch gamers, 60hz would be their big thing to ditch and that changes the upgrade decision dynamic. Also if you want to record/stream its clear a 2500K/3570 is not going to be enough any longer for that.