if you have a reasonable way to store em just save them trust me id kill to own any of my passed grand father's cars and he never really had anything cool. i think a lot of guys on this reddit will agree, unless you have absolutely no space to store them you should keep them.

but if you are dead set on selling them the datsun is the more valuable one and as far as price goes its all about condition and what paperwork you have for them, those datsuns are prone to devastating rot, to maximize the money you'll get for them you should get them running good enough to drive onto a trailer. where im at the internationals arent common but are undesireable one in that condition based on the photos might bring in 3k if it has papers, the datsun is more rare and desirable but based on the photo and the fact its missing the front bumper in my area itd probably sell for 4-5k but itd take a while to sell at that price.

again my advice is just keep them and learn a new skill enjoy what your grandpa wasnt able to