I would try to find a junkyard part from an Eldorado. The interchange manual, if someone has one, would be the best place to check. When you search on eBay the places which are actually junkyards do that check themselves and include the info in the listing. So look for Eldo only first and see if they list other cars. The Toronado hinges would be my guess if anything else uses the same PN.
One other note: Even for Chevelle where there is TONs of aftermarket support I would never again buy an aftermarket hinge. We tried a new set from a well known Chevelle part supplier and they looked correct but never worked which actually, after lots of manipulation, cause damage to the hood paint in the area. Never again. We sent the originals out to Willie who I referenced in an earlier post.
Scott