Motherboard liquid cooler suggestions

Current specs
Intel db75en
Intel i5 3rd gen 3450
Gtx 970 amp extreme edition
Samsung evo 120
PSU corsair vs 650
Liquid cooler h50 corsair

Currently they are on LGA 1155 mobo

I just killed my old motherboard
And now I am planning to buy i7 4790k

There are three motherboards I have in mind and all of them are asus z97 series based. Want to buy only asus..
Z97 A
Z97 k
Z97 c

I want to know that whether I should upgrade and get 1150 mobo and new processor or not!

(I have no plans to put dual gtx 970 bt plan to use secondary gfx card (gtx560) as phyx dedicated card)
If yes then
1. Which mobo I should go for and why?
2. Will the old h50 will be fittable on my new board or not!

Any new advise also appreciated!
Thank You