The UO-8 would be a decent conversion. They have a reputation for a pleasant ride and they're ubiquitous enough that nobody will get on your case for desecrating a classic bike. The metric thread bottom bracket and steer tube are probably the most significant conversion issues. If the headset and BB cups are ok, keep them and just source a BB spindle for whatever crank you decide to use. Otherwise, metric thread replacements are available but may cost more than you're willing to invest in the project.