Learn something new every day! Although I would hate to have to actually find some- let alone any decent 13" tires to mount on them! They're out there, but if you think the 14" selection is bad, 13s are worse. Just went through this with a buddy's Corvair.
Yeah probably sticking with 14s mostly for this reason. I really like to keep it ugly and stock looking. Got some 14in steel wheels with later dart hubcaps