Dear A K:

You wrote:

Can one say:

a. I have a plan for you to get rich.

b. I have a plan to get rich for you.

I have a plan for you. You can use it to get rich.

You may hear English speakers say such a sentence either way, and it does mean the same thing. However, sentence a is more easily understood. Because the phrase “to get rich” immediately follows “plan” in sentence b, the listener is going to first think that the speaker has his own plan to get rich. That confusion is eliminated in sentence a because the listener understands immediately that the plan is for him, not for the speaker.