Need help assessing this 1965 Dodge Dart 270 4-dr sedan

Okay! I got it for $3500 and I got her home without incident! Now the hard work begins... First order of business is to get new tires. We'd like to get white walls, but I'm having trouble figuring out what size tire to get since it has both 185/80/R13 and 175/70/R13 on it. By the looks of it, 13-inch tires are mostly trailer tires these days. Can anyone suggest a suitable size and WW tire that's under $70/tire? Where do you guys look for tires on these old-timers? Most sites don't go back to 1965. Thanks!