Here you go on the on the Intel side with a 8700K. I have added the Gigabyte Z390 Gaming X motherboard which has a great 10 phase VRM and is cost effective. RAM at DDR4 3200 and a decent Gold power supply. A 500GB NVMe Crucial P1 SSD which is very fast. This should give you an idea as to what you can do. The 8700K is a great Gaming CPU but if you can get the 9700K even better as it is right up there with the 9900K on the gaming side.
I have not added the GTX 1080Ti as I presume you already have it...but if not just add...
You could go to a 9700K which is only about $25 to $30 more
PCPartPicker Part List:
https://pcpartpicker.com/list/4t3NNq
CPU: Intel Core i7-8700K 3.7 GHz 6-Core Processor ($354.99 @ Newegg)
CPU Cooler: Cooler Master MasterLiquid ML240L RGB 66.7 CFM Liquid CPU Cooler ($65.89 @ OutletPC)
Motherboard: Gigabyte Z390 GAMING X ATX LGA1151 Motherboard ($129.99 @ Newegg)
Memory: Corsair Vengeance LPX 16 GB (2 x 8 GB) DDR4-3200 Memory ($69.98 @ Amazon)
Storage: Crucial P1 500 GB M.2-2280 NVME Solid State Drive ($66.89 @ OutletPC)
Storage: Western Digital Caviar Blue 1 TB 3.5" 7200RPM Internal Hard Drive ($42.89 @ OutletPC)
Power Supply: EVGA 650 W 80+ Gold Certified Semi-modular ATX Power Supply ($76.88 @ OutletPC)
Total: $807.51
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2019-10-15 12:06 EDT-0400