Try QTR - Quad Tone RIP, it's shareware but only $50 to buy, it only works with Epson printers, I've used it with my R3880.Alan, do you use the Advance Black and White driver with the P600 and if so, how neutral do you find the results. I use the Epson R3880 and by default, the blacks tend to be a little warm.
A friend of mine is an ex Ilford engineer and LF photographer and goes on holiday with Roy Harrington (QTR software developer) and others like Howard Bond, his work and prints made using QTR are superb. It's a B&W only RIP but gives excellent control over image colour etc and is very easy to use, there's also profiles for making digital negatives for alternative processes. Knocks spots off the Epson drivers.