I picked up a late 80's Merckx Corsa Extra over the weekend which has Record and Dura Ace components. It has indexed downtube shifting which works flawlessly with Shimano 7401 shifters, rear derailleur, and rear cassette. The hubs are Record. I am interested in knowing whether or not I could put a Campy (preferably Record) rear derailleur on there and have any hope that it would shift properly in indexed mode. Anyone have any experience with this and want to share problems, successes, advice, etc? Thanks for any info!

might. I've seen combos like that work okay. The original (c-record?) derailleur was more than likely swapped out because it wouldn't work with the shimano shifters (maybe not, though...the guy just might have assumed...).

The C-Record derailleur was a remake of all of the campy derailleurs up to that time, massively restyled. No slant parallogram. If you go up into the '90s you'll find a nice athena or so, works just like the shimano that's on'er now.

Put your serial number up...there are people here interested in that detail.

And, oh yeah, we need to see some pictures.

If it works flawlessly, why change it?

ach, it is not campy, of course.

Try it and see. From the little I know, the indexing is *mostly* in the shifter, the derailleur is secondary, at least in a 6-7 speed setup.
A matched shifter and rear cogs should get you close.