Looks legit, definitely aftermarket bridge and E tuner, and I think aftermarket brass nut and strap lock buttons. It would be helpful to unbolt the neck and see the date stamp on the neck and body. You could also get date codes from the potentiometers. I've never seen that much rust, it may have been stored in a humid area? I would put a new set of strings on it and play it as-is.
I'm impressed with this bass...it was tuned maybe 3-4 yrs ago and it still is in tune. (I'm not an expert on disassembly but I'll try to get more pics?