Can you guys give me some advice on set up for a custom pc?

Solution
It would work, but that's a very weak CPU. You can fit both an i5 and R9 280 into your budget.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i5-4460 3.2GHz Quad-Core Processor ($174.99 @ NCIX US)
Motherboard: ASRock H97 PRO4 ATX LGA1150 Motherboard ($81.00 @ SuperBiiz)
Memory: A-Data XPG V1.0 8GB (2 x 4GB) DDR3-1600 Memory ($59.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($51.85 @ OutletPC)
Video Card: Gigabyte Radeon R9 280 3GB WINDFORCE Video Card ($174.99 @ Newegg)
Case: Corsair 200R ATX Mid Tower Case ($49.99 @ Amazon)
Power Supply: XFX 650W...
It would work, but that's a very weak CPU. You can fit both an i5 and R9 280 into your budget.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i5-4460 3.2GHz Quad-Core Processor ($174.99 @ NCIX US)
Motherboard: ASRock H97 PRO4 ATX LGA1150 Motherboard ($81.00 @ SuperBiiz)
Memory: A-Data XPG V1.0 8GB (2 x 4GB) DDR3-1600 Memory ($59.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($51.85 @ OutletPC)
Video Card: Gigabyte Radeon R9 280 3GB WINDFORCE Video Card ($174.99 @ Newegg)
Case: Corsair 200R ATX Mid Tower Case ($49.99 @ Amazon)
Power Supply: XFX 650W 80+ Bronze Certified ATX Power Supply ($56.49 @ NCIX US)
Optical Drive: Lite-On iHAS124-14 DVD/CD Writer ($16.95 @ OutletPC)
Monitor: LG 22M35D 60Hz 22.0" Monitor ($89.99 @ NCIX US)
Wireless Network Adapter: Asus PCE-N10 802.11b/g/n PCI-Express x1 Wi-Fi Adapter ($12.11 @ Newegg)
Total: $768.35
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-12-16 13:16 EST-0500
 
Solution
Will it work? Yes... but you could spend the budget a bit more wisely for a gaming rig. If you could add an SSD (Crucial MX100 or Samsung 850 EVO) you would be in great shape, but as the below system is better all around over your original AMD build.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i3-4150 3.5GHz Dual-Core Processor ($99.99 @ Amazon)
Motherboard: ASRock H97M Anniversary Micro ATX LGA1150 Motherboard ($71.98 @ Newegg)
Memory: Mushkin Silverline 8GB (2 x 4GB) DDR3-1600 Memory ($59.99 @ Newegg)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($53.68 @ Amazon)
Video Card: Sapphire Radeon R9 280X 3GB Dual-X Video Card ($229.99 @ Amazon)
Case: Fractal Design Define R4 w/Window (Black Pearl) ATX Mid Tower Case ($79.99 @ Newegg)
Power Supply: SeaSonic 750W 80+ Gold Certified ATX Power Supply ($89.99 @ Newegg)
Monitor: LG 23MP55HQ-P 60Hz 23.0" Monitor ($137.97 @ NCIX US)
Wireless Network Adapter: Rosewill RNX-N250PCe 802.11b/g/n PCI-Express x1 Wi-Fi Adapter ($18.98 @ Amazon)
Total: $842.56