Technically you can do anything.
The problem is do things line up? And then what adaptors do you need to make it fit?
Step 1 would be removing the front plastic bezel from metal frame and compare the anchor points, spacing and curvature, the SE(SE\30) bezel is flat while the Classic/Classic II is curved outward.
Since you are doing a Classic to SE (SE\30), you need to see if the SE(SE\30)'s metal frame fits the Classic bezel an lines up with its anchoring (screw) points.
The rest of the job is to make the parts fit, which I will not go into detail here. It's doable to a point and that point depends on how much work are you willing to put in to make it so.
EDIT: A major problem is going to be how the floppy drive lines up with the bezel's slot when you put that in later.