The back is the important part of an SE/30 upgrade because of the new back. The same also goes true for Classic --> Classic II upgrades and any upgrade involving a II/IIx, IIcx/IIci, or LC/LCII/LCIII.

The only difference in the front of an SE/30 is that an SE/30 front does not accommodate a second floppy drive. Finding a slot cover for an SE whose second floppy was removed during upgrade (necessary since the SE/30 only supports one on its logic board) is much easier since the CRT doesn't have to be removed.