Keep the 2500K by all means. It is still an excellent performer and IMHO, better than the Haswell and Ivy Bridge versions. Find a Z77 board, a Cooler Master Hyper 212 EVO and some Crucial Ballistix Sport VLP RAM. I have this RAM and it is very, very good. Compatible with almost any cooler on the market.
+1 for this
I've also had great success with G.Skill RAM.
The Hyper 212 EVO has very flexible mounting hardware and can mount horizontally or vertically, and the fan can be mounted in push or pull. So RAM clearance will be a non issue.