Well you are on the right track avoiding that disgraceful E10 product. Many a Victa prism fuel cap has succumbed to that garbage in my experience, necessitating a time consuming tank clean out and fuel tap replacement.
I'm sure a good old 1960s motor isn't made up of exotic Ferrari grade metals and standard 91 octane unleaded will work fine (where you can find a pump!).
As for oils, I'm sure a current 40 weight oil as you mentioned hasn't changed sufficiently to do any harm. Others here will have more knowledge on this.
