Don't bother is my opinion.
It would be good to see some dyno data on 180 vs non-180, Ive never seen any but in any case, 180 equal-length is designed to get the absolute max power at one given RPM. Great idea if you're just curcling the high banks at the Packard Proving Ground (we've actually done that!).
But for street, dragracing, roadracing, even short track, the engine sees a range of RPM, so putting all the peaks at one RPM is of little use. The typical 90-180-270 unequal length headers are fine IMHO, they will just give smaller peaks but spread over a larger RPM range.
I think avoiding restrictions and sharp bends/turns, especially right at the exhaust port, matters a lot more. I HAVE seen dyno data to support that (though not on a Packard!)