How to upgrade to "Older" derailleurs

I have a Schwinn Paramount that is in very good condition. Right now it has
Shimano 600 components and 8 gear rear derailleur.
What I would like to do is upgrade the derailleurs to Campagnolo Record set.
Since the frame is designed for 8 gear cluster, I don't believe anything more than an 8 gear cluster will fit.

Since every year Campy and Shimano come out w/bigger clusters, I can't upgrade to them. So any ideas where a person can get Campy Record 8 gear components.

Doug

 

I had a Paramount OS built when Ultegra was 7 spd. That frame accepted 10spd Campy without a problem.

 

If the freehub body on your rear wheel uses a lockring, then you can probably install a Shimano-to-Campagnolo 10-speed conversion cassette on it ...

I think the some of the 8-speed Shimano freehubs were spaced with a slight offset toward the driveside (well, one of my DA hubs was configured that way) -- if that is the case, you will need to move the 1mm washer from the drive side (located between the cone & locking nut) and move it to the non-drive side AND re-dish/re-true your rear wheel, accordingly.

Some 8-speed Shimano rear hubs used a threaded last cog ... so, those freehub bodies would have to be swapped for a freehub body which uses a separate lockring.

A 10-speed Campagnolo ERGO shifter when mated with most 8-/9-speed Shimano rear derailleurs (there may be exceptions which I have not encountered) will index to the cogs on either an 8-speed Campagnolo OR Shimano cassette.

A 10-speed Campagnolo ERGO shifter will mate with most 8-/9-speed Shimano rear derailleurs & a 9-speed Shimano cassette if you use the hubbub.com alternate anchor position for the rear derailleur cable.

 

As has been said above, you should have no problem as you probably have 130mm spacing. (or you've already tweaked the steel enough if it was 126mm originally, as Alienator said).
Here is a concise chart of standard dropout spacings:
http://www.sheldonbrown.com/gloss_sp-ss.html#spacing

 

Thanks for th input. I will see what I can do ....

Doug

 

I've got a paramount I've done this to, any good size shop should have a pair of dropout alignment tools and can cold set the spacing if needed [I didn]t need this].
The only problem I've encountered was trying to run an 11 tooth I couldn't get enough clearance without a small washer on the outside of the axle, I just didn't like how it looked so went back to a 12.