Replace window with New Construction window
You almost certainly can't use New Construction windows without at least removing some siding. This type of window is intended to be installed before the siding is on, so you can integrate its built-in flange with the wall's water-resistive barrier (tar paper or Tyvek housewrap, usually) using tape and good lapping, all of which requires several inches of space on all sides to work. If you're not planning to remove the siding to expose your wall's WRB, then there is no advantage to using a new construction window.

With Replacement windows, you can order them in whatever size you want, so getting a window that's too small shouldn't be a concern.