I believed the consensus is that there's no real performance increase in going from Ivy to Haswell, especially considering Ivy's overclocking potential (which doesn't face heat problems like Haswell).
If emulation is one of the reasons for a new build though, better to go Haswell.
Oh yeah totally forgot the IPC increases, architectural improvements, AVX2/FMA3 instructions, and superior chipset don't count.
Though if you don't want to future proof then be my guest!
Overclocking is far from the be all end all, are you forgetting the downsides of it?