I’m adding some additional info here as well that may assist you:
The community has put together a forum thread with their machine setups and what their experience is with the engine. The post is titled: [Compatibility List] Unreal 4 - Hardware Feedback]
Take a look there and see if anything matches what you are have or is close. This will give you a better idea than I could about what will best work for you.
I do want to mention as well that the engine is capable of scaling the detail down to give you a better user experience but it will lack features when this is done though. I’m linking the Engine Scalability Settings here to see if this may assist you in what you’re looking for. 
Thank you!
Tim