You can get 185/80 R13 WW tires from Maxxis tires. The tires are pretty decent riding and handling, although it seems like they are a little rough for the first mile or so. But that's on a car that is not a daily driver and sits for a couple of weeks at a time. This size tire fills the wheel wells nicely and is the closest diameter to the original bias ply tires. I got five tires for $499 with shipping a little over a year ago from Universal Vintage Tire. Here's Maxxis' web site. They have an alert about this size tire, which you can order direct from them.
http://www.maxxis.com/