Sorry for a reply after so much time, but the OP's situation is somewhat rare, so I thought I could help.
The circuit rev 04 and 05 are unfortunate ones, with several bad decisions cascading into a fizzy, nasty sounding mic that is mostly derived from the sub-board, which completely replaces a FET. This was due to Neumann's difficulty in sourcing high quality 2N3819s. However, there is a fix. I had mine modded by James Brian at the mic shop. He did the usual mod to remove/modify the high and low pass filters inherent to U87s that enable them to conform to German broadcasting standards, but make the mic sound less musical. He can also remove the sub-board, and add a true FET. He has one that he likes, but you can request an actual 2N3819, and he might be able to accomodate you. Also, I recommended another change that marked a first time mod for James. I asked him to lower the capsule polarization from 60v to 48v. (48v is what classic Neumanns used). This change "relaxed" the tone of the mic, and made it less brittle. There is a slight loss in sensitivity, but U87s are so over-the-top loud anyway, it actually helped. (I got the idea when I tried a Miktek that had the 48/60 switch, and noticed how much better it sounded in the 48v setting).
I love my U87 now, and it can hold its own against anything, including my vintage original C12 and U67, plus a whole bunch of modern mics I own. Try it!