Since you mentioned ladder bars, assuming its a Chevelle. First step is order the shipping report from the link below and go from there. You don't give any details on the ownership history and no mention of original paperwork, so it's difficult to provide any insight or help without knowing more.
All of the parts you've mentioned were widely available via mail order or in store purchase from a variety of sources back in the day, so their presence doesn't necessarily mean anything. Not ruling anything out, but you've got to do the leg work and offer some details / pictures for anyone to provide any meaningful advice. I've owned 5 documented BM cars, so have some knowledge and firsthand experience.
https://www.chevymuscledocs.com/