First, there's no such thing as having only one vintage machine, so you might as well plan on getting as many as you "need" to do what you want.
That being said, I think you can find one machine to do most of what you want. Here are pictures of two I have, the first is a Japanese manufactured machine from the 1960s with built in patterns, but no capability for cams. You can find lots of these Japanese made all metal machines with different capabilities.
The second is a Singer 503 with basic features but cam capability, including a necessary cam to do basic zig zag. You mentioned a 401 which has built in patterns as well as cam capability. I am in the middle of working on my first 401, so I can't tell you much, but you can search the board. The Singer 500 Rocketeer is much like the 401, only much neater looking in my opinion.
I think you may be limited only by your budget.