I don't quite understand what you are asking here.Those big arpeggiated chords that come at the end of the Trio development section in A Major? At the B-flat minor return. There?If so, you roll the left hand from top to bottom simultaneously as you roll the right hand from top to bottom. Together. A big, fat whoosh. VAROOM! The voicing happens of itself. And in tempo? Well, yeah, but the writing sort of demands intense emphasis on these chords . . . you can't help pulling back from the tempo a bit, which I think sounds dramatic, but they CAN be played in tempo, too, which also is an exciting effect. Of course, by the time you get to this spot in performance, you're so frickin' tired you don't much care what happens. Hope I answered your question.
- strike the LH Bb octave with the F on the downbeat of m. 553.