Leukybear 

Anybody have 1st or 2nd hand experience with wheels manufacturing's 8 speed conversion kit?

Supposedly it allows you to use a 8 speed shimano freehub cassette with a 8 speed campy RD/ drivetrain through means of re-spacing. Thus saving you the trouble of having to get a campy specific wheelset.

Link: 8 Speed Conversion REVIVED LIMITED RELEASE - Cassette Conversions - Rear Drivetrain - Small Parts

The product page is pretty lacking in technical details in terms of compatibility so any insight would be appreciated.

RobbieTunes

Works like a charm. Makes Shimano 8/9/10 wheels work just fine with Campy 8.
Been there, done that.

Dave Mayer

Shimano 8-speed spacing is 4.8mm cog center to center, and Campy 7 and 8 speed is 5.0mm. Not much a difference practically. I have been running Campy 8-speed Ergopower levers on an unmodified Shimano 8-speed cassette for the last 2 weeks with no apparent deterioration in shift quality.

If you're really fussy, I suppose you could use a Shimano 8-speed cassette with some or all of the 8-speed spacers replaced with the slightly thicker 7-speed versions. Shimano 7-speed spacing is 5.0mm.

In order to do this, I would go to my local bike Co-op, and pull one of the discarded 7-speed Shimano cassettes out of recycling. Then I would break it apart to get at the spacers.

Dfrost 

I have the Wheels Mfg conversion kit on three (out of our four) bikes and they work very well. I was pretty frustrated with the limited cog sizes and short wear life of the nearly extinct Campy 8-spd cassettes, and have a drawer full of loose Shimano cogs from 7 and 8-sped cassettes. The only catch is that the 1997 Campy Chorus RD on my wife's bike seems to prefer having matched cogs, although it shifts wonderfully when I get the cogs right (both SRAM or Shimano work equally well), while the Sachs New Success RDs with Campy-built Ergo brifters I have on my bikes don't care a bit about what cog is next to what. So I can build all sorts of custom cassettes for those bikes.

Not sure if the kit now includes a lock ring with longer threads, but that is very helpful because of the extra cassette stack height with the thicker spacers.

Dave Mayer makes a good point about Shimano 7-sped spacers. I really should try them sometime to see how they work in comparison the the Wheels Mfg kit.

FWIW, my wife's Campy Record Exa-Drive hub didn't seem any smoother or better designed than the Ultegra I used for her replacement wheel with the Wheels Mfg kit. I'm now using Ultegra or similar grade Deore XT rear hubs with great success on all of our bikes, as well as my three adult kids' road bikes.