I personally wouldn't overclock on a B350M motherboard. I'd recommend a X370 since you can achieve a way better overclock and of course "safer"... B350 Motherboard technically aren't made for overclocking as much as X370 are since they usually have less power phases and will stress the mobo.
Check out this build!
PCPartPicker part list:
https://pcpartpicker.com/list/QZ72M8
Price breakdown by merchant: https://pcpartpicker.com/list/QZ72M8/by_merchant/
CPU: AMD - Ryzen 7 1700 3.0GHz 8-Core Processor ($299.44 @ OutletPC)
Motherboard: MSI - X370 SLI PLUS ATX AM4 Motherboard ($120.98 @ Newegg)
Memory: G.Skill - Ripjaws V Series 16GB (2 x 8GB) DDR4-3200 Memory ($129.99 @ Newegg)
Storage: Kingston - A400 120GB 2.5" Solid State Drive ($49.99 @ Amazon)
Storage: Hitachi - Ultrastar 7K4000 3TB 3.5" 7200RPM Internal Hard Drive ($65.99 @ Amazon)
Video Card: MSI - Radeon RX 580 8GB GAMING Video Card (2-Way CrossFire) ($239.00)
Video Card: MSI - Radeon RX 580 8GB GAMING Video Card (2-Way CrossFire) ($239.00)
Case: Fractal Design - Focus G (Black) ATX Mid Tower Case ($49.99 @ NCIX US)
Power Supply: Corsair - CXM 750W 80+ Bronze Certified Semi-Modular ATX Power Supply ($54.99 @ Newegg)
Total: $1249.37
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-06-10 13:09 EDT-0400
Be pretty LIT!
Sounds like you won't be playing too intensive games? So maybe just get one RX 580 and see if that's enough , assume 1080P? If so it should be plenty... RX 580 in CF should perform a bit better than a GTX 1080 if the game supports it
Even then only 1 is fine bud. Good Luck!