Build Help

I currently own a R9 290 Tri-x and a Radeon HD 7850 and I'm looking components to make it work with expansion options.
I have a 230W power supply (or so) that needs an upgrade (is 5 years old) so I need some advise on that.
I have an i7 processor and a motherboard with 1 PCIx16 and 3 PCIx4.



So in conclusion I need help deciding:
  - Power supply
  - Motherboard?
  - GPU's?


I want to be able to expand or add more GPU's later when required.
Money's not a direct issue here, I'm just looking for builds to work towards and get it working quick.