wrote:

-snip-

On the way back Delta damaged the gear group in the back.

Before I can start looking for the replacement part I'd need to know
what type/year the campagnolo group is.

-snip-

Are you sure that the rear derailleur is damaged?
Could it be that just the derailleur hanger is bent?
Is your purpose to totally restore it to new condition?
If not, you can use a newer & probably superior derailleur for less
money.
Also, I could be mistaken, but the chain appears too long. If it is too
long, it will shift better when shortened to the correct length.

My $0.02, Good luck, John