That's not too bad as a simple passive filter.  However, you're going to have to get the inductors to better than 2% accuracy channel-to-channel, and the capacitors should be better than that, if you want a reliable stereo image.  Also, don't install it too close to a mains transformer, or you'll get the dreaded hum!

I designed a replacement for the 15kHz filters in the Pro IV, using op-amps with gyrators emulating inductors.  It was published some years ago in EDN.  I'll dig it out and post it here.  I designed a PCB for it that was designed to fit above the Pro IV coder PCB.  I'll put that up too.  It's a single-sided board, and it sounded significantly better than the passive Toko BLR filter.  It also suppresses out-of-band signals better than the Toko jobs.

I'll post it in the next day or so.