If you are not sure (and would and should is not an easy one) I would (should?) change it to something else.
I suggest:
I wish to apply for ..or
I am applying for...
Years ago we used to use should instead of would for the first person (I should and We would) just like we used I shall and We shall instead of I will and We will. Due to using I'd and I'll etc we now use would and will for all persons. Should now means ought to and Shall in questions as in Shall I open the window?
As factor suggests I'd use I wish to....