Sounds and looks like a nice bike. I would target a Continental UltraGatorskin tire. I always find Panaracers to feel funny due to the thick center strip.
Saddles: I like Selle Italia Prolink and the Specialized Alias.
Frame: If it's built for 126 mm rear hubs, spread it to 130. Then you'll be able to upgrade to modern geartrains anytime in the future.
A fine find, IMHO, but I like vintage steel!
ken