Upgrading rig - what's the best GPU/CPU I need/my rig can handle/I can afford?

[fillasophy]

Hey all,

So, I was pretty active here for a few months about 3-4 years ago, but haven't done really any building since then, so I have no idea what's what anymore. Your help figuring out the best I can work with starting with what I have would be appreciated.

Anywho, so I have two rigs I've built: one for gaming, one HTPC. The home theater PC has been replaced by my XBOX (due to issues with the HTPC and the upcoming Xbox TiVo update) so it's parts are all fair game. My goal with this is to build the best SINGLE computer I can from the parts I have, while possibly upgrading the GPU and/or CPU to run newer games at high or better settings. I have a max $200 budget for upgrades (less if possible), so I'd like to avoid purchasing a new power supply or mobo (I imagine what I have should be good enough anyway).

I play bigger multi-platform games (eg: Titanfall, Star Wars Battlefront, etc) on console, so this rig is/will be running mostly lower-demand games and one or two bigger ones so it doesn't need to be a complete monster... My current target is ARK: Survival Evolved.

Specs:

Current Gaming Rig:
Mobo: GIGABYTE GA-880GMA-USB3 AM3+ AMD 880G Micro ATX
CPU: AMD Athlon II X3 455
CPU Cooling: Cooler Master Hyper 212 Plus 120mm
GPU: GIGABYTE ATI Radeon HD6850 1GB
PSU: SeaSonic S12II 620 Bronze 620W ATX12V V2.3
RAM: 12GB total: G.SKILL NS 4GB (2 x 2GB) 240-Pin DDR3 1333
--------------------G.SKILL Ripjaws 8GB (2 x 4GB) 240-Pin DDR3 1600
Storage: Samsung 1 TB Spinpoint 7200 RPM 32MB Cache SATA 3.5 inch
Case: Antec 300 Illulsion Case w/ custom mod (cannot mount fan to door)

HTPC:
Mobo: ASRock FM2A75 Pro4-M FM2 AMD A75 (Hudson D3) Micro ATX
APU: AMD A6-5400K Trinity Dual-Core 3.6 GHz Socket FM2 65W
CPU Cooling: Stock
PSU: SeaSonic 80 Plus SS-350ET Bronze 350W ATX12V V2.31
RAM: G.SKILL Ripjaws X 4GB (2 x 2GB) 240-Pin DDR3 1866
Storage: Boot: Samsung 840 Series 2.5 inch 120GB SATA III SSD
---------General: Western Digital Caviar Green WD15EZRX 1.50 TB 3.5"
Case: SilverStone Aluminum/Steel Micro ATX Media Center/HTPC Case ML03B (does not have clearance for standard-sized GPU or large cooling fans)

S!@#s and giggles:
Optical: Optical: 3 total: 1x Blu-Ray Reader and 2x CD-RW multi-drives
Peripherals: Redragon Karura K502 USB Gaming Keyboard
Redragon M601 CENTROPHORUS-2000 DPI Gaming Mouse

Basically I'm thinking I should swap the storage between the two rigs, giving my gaming rig more space and a SSD, while upgrading the GPU via cyber monday deals to get the most bang for my buck. I don't overclock really at all (though I suppose I wouldn't be against learning around the holidays) if that makes a difference to anything...

Thoughts?
Thanks in advance!!