Combining 24 fps and 30 fps footage?

[black_magic100]

So I just created a 24 fps timeline, but some of my old footage is 30 fps. It is my understanding that premiere will automatically interpret the 30 fps footage as 24 fps and since it is dropping frames it won't look as bad as if it has to add frames (24->30fps).

However, I just realized that I am shooting in two different resolutions and now my footage has black bars on the side. AS long as I scale in the 30 fps footage to meet the composition size I should be fine correct?