I've heard the opposite, that the new ones can also break and not have enough strength to lift the lid with the spoiler. That could be incorrect installation or using rods for standard deck lid with no spoiler too.
For a 40 year old part, they are usually perfect, haven't broken or become weak. Based on that I'd be happy to install used, just need to find a good set that have been removed and happy to ship around the world, otherwise, probably the same with shipping new item. Check the insulation sleeve as well, I think it was inserted prior to assembly so a bonus if still intact and in place.