Yep alloy tank is ok for the road.
As for buying a Goldie, what sort do you want, there are 5 types of engine, two types of frame and about 4 main types of style (Clubmans, Touring, Scrambles & Trials).
Make sure it has a Gold Star Club cert so you can be sure its genuine, there are alot a very very good fakes out there as it is very easy to build a Goldie from mainly new parts.
There is one on ebay at the moment, if it is what is says it is, then convert it back into a Catalina, as they are stunning bikes.