You want the Model 3770s at Allied. No nickel, no brass, and it's audible to me as I've A/B'd with the gold Daytons. I buy the $4 round plastic cup terminals from PE, remove the terminals and replace them with the Pomomnas, an exact fit.
I like the pure copper ones, as well, with no plating. I still have an extra set from Percy that I haven't used yet... Copper sounds the best, to me. I also take the stock ones out of the PE cup and "reinstall" the good copper ones. Sometimes takes a little hammering, but then they're in to stay. I use twisted OFC magnet wire inside, all connections soldered.