I would go for a z270 mobo and an overclocked CPU. Almost the same price. You will have to buy a better cooler and the one I added is one of the best air cooler.
PCPartPicker part list:
https://ca.pcpartpicker.com/list/bcJgWX
Price breakdown by merchant: https://ca.pcpartpicker.com/list/bcJgWX/by_merchant/
CPU: Intel - Core i5-7600K 3.8GHz Quad-Core Processor ($299.99 @ Memory Express)
CPU Cooler: CRYORIG - H7 49.0 CFM CPU Cooler ($46.75 @ Newegg Canada Marketplace)
Motherboard: Gigabyte - GA-Z270X-Ultra Gaming ATX LGA1151 Motherboard ($201.00 @ Vuugo)
Storage: Western Digital - BLACK SERIES 1TB 3.5" 7200RPM Internal Hard Drive ($99.50 @ Vuugo)
Video Card: EVGA - GeForce GTX 1070 8GB SC GAMING ACX 3.0 Black Edition Video Card (Purchased For $639.99)
Case: Corsair - 200R ATX Mid Tower Case ($64.99 @ Memory Express)
Power Supply: EVGA - SuperNOVA G2 750W 80+ Gold Certified Fully-Modular ATX Power Supply (Purchased For $149.99)
Operating System: Microsoft - Windows 10 Home OEM 64-bit ($134.99 @ NCIX)
Other: G.SKILL F4-3200C16D-16GTZR Trident Z RGB Series 16GB, 288-Pin SDRAM DDR4-3200MHz (PC4 25600) Desktop Memory ($209.99 @ Newegg Canada)
Total: $1847.19
Cost of parts you don't have yet: 1057.21
You can add an M.2 ssd in the future and upgrade to a 7700k though the 7600k is great for your GTX 1070
Good Luck!
(PS: you can save ~100$ by going for low performance/cheaper parts.