How to switch between two HUDs?

Hey guys,

Wondering if you know how to switch between two HUDs while aiming?

For example, I want to have this as my normal HUD

http://i.imgur.com/GDUl0X2.png

And I want this as my HUD while aiming.

http://i.imgur.com/egLFssQ.png

How can I switch between these via blueprint? (Pictures would be appreciated.)

Thanks, Joel.