Yes, your sentence makes sense—although I find it slightly awkward.
In interpreting what you're saying, I consider something like this:
You can make your juice be mixing orange and apple in any ratio you like (for example, 1:3, 1:4, and 2:3)—so long as you always use less orange than apple.
Here's the problem with using proportion in the latter part of your sentence:
3 : the relation of one part to another or to the whole with respect to magnitude, quantity, or degree : RATIO
That's the third sense of Merriam-Webster's definition of proportion. Note that it's synonymous with ratio. (However, in terms of syntax, ratio and proportion are used differently.)
So, in reading the sentence, it makes me wonder why you are bothering to use another single word that means the same thing. In other words, these sentences are synonymous:
Use any ratio of orange to apple, but only if that ratio results in less orange than apple.
Use any ratio of orange to apple, but only if the proportion of orange is less than that of apple.
However, it's often strange when a synonymous word is suddenly introduced when the same word can be used again just as well—or things can be rephrased.
In reading the second version here (and your own version) I stop when I hit proportion and get puzzled. I wonder why a different word is being used, and if it's meant to be expressing something different than the first word. So, I go back and read the sentence from the start again. I do this about three times before I assume I'm not missing some intended difference, mentally shrug my shoulders, and carry on.
So, while your sentence is accurate, I had to read it several times in order to parse it and understand how proportion was being used, and what you were actually trying to convey.
If only in terms of avoiding confusion on the part of readers, I would recommend dropping the mix of ratio and proportion and use only the first word—either repeating it or expressing it differently in the second half of the sentence.