You would need to buy a new AM4 socket motherboard and DDR4 RAM if you want a Ryzen CPU. I would say wait until you upgrade your GPU and see how it performs. Then decide if you want to spend the money to upgrade to Ryzen, though I believe it would be worth it.
The GPUs you listed would all be a good choice if you can find them at a decent price.
You can change the power supply, EVGA 500B is not the best but it's not the worst either. I would suggest getting this PSU instead of the 500B.
PCPartPicker part list /
Price breakdown by merchant
Power Supply: SeaSonic - S12II 620W 80+ Bronze Certified ATX Power Supply ($47.79 @ SuperBiiz)
Total: $47.79
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-07-26 18:01 EDT-0400
*Edit: Just saw your updated post.