hold on... how many threads does lightroom even use? overclocking isnt just about max cpu usage rendering apps, everything singlethreaded is entirely bottlenecked by the clock instead of the amount of cores, so the performance that comes with an OC will be quite linear
if lightroom is well threaded, could go for a 4core8thread cpu & not bother overclocking (same choice as someone looking to do 3d cpu based rendering)
but if lightroom is only 4 threads or even 2, an overclock would be important, a 4core4thread cpu would be $100 cheaper & faster when overclocked
(speaking of OP's story, pretty sure core2 days were harder to tweak/stabalize than now)