I would suggest selling the 980 you have now when Pascal releases and buying one GTX 1080.  This way you can avoid the heat and power cost of a SLI.  You have to factor in that its an additional 170W when gaming, or about 2 cents an hour.  You also have to deal with the extra heat of an SLI in the case.
 
Otherwise, if you want to carry through, the two 980's would work together.  It would probably be best for the blower style to be on top, but you could try it both ways and see which is best.
 
Its the 970's that EVGA made that do not all work together.

You make a good point on waiting for the 1080 release. My only concern is availability over the next few months. I'm already seeing the 1080's going for over $1,000 on ebay for the lucky few who were able to get the preorders. Since I'm new into the pc gaming world how likely are these cards to be available around July? are new release cards typically sold out for months at a time? Or is it just upon initial release? I can probably hold out until July or so but with a 1440p 144hz monitor im itching for an upgrade. I'm also taking into the consideration that I would need to upgrade my ps for sli as I'm only using a 650w right now.