Same airfoil? That will make as much if not more difference than span/chord.

Had a hard time figuring out what was going on here. Maybe we can start with clearing up some terms. Wings are measured by span and chord, not length and width. The span is the distance from tip to tip. The chord is the distance from the leading edge (LE) to the trailing edge (TE). If I understand, you will be increasing the chord?

This will have several effects, but most won’t be noticeable unless the change in chord was significant. It is hard to know what it will do in flight without more info, but most likely it will have more drag (due to increased wing size) a worse glide ratio (again due to increased wing size), a slower stall (due to increased efficiency from longer chord) and less pitch stability (due to increased wing area.) But again, what are we talking, like a increase of 1-2” in chord on a wing that was already 10-12” or so? You won’t see much diff in that increase unless you changed airfoil.

Spiral Stall speed has little to do with the span of the wing. It is primarily a characteristic of the airfoil and wing loading. The high aspect ratio (large span short chord) is to improve lift/drag ratios.