It's not clear to me how you'll achieve anything better via an embedded Excel object, since you'll have the same issues with variable-length content there. Granted, such an object can be re-scaled, but that doesn't address issues of text-wrapping and font sizes. That said, you could try code like:
Code:
Sub Demo()
Application.ScreenUpdating = False
Dim objOLE As Word.OLEFormat, objXL As Object
Dim R As Long, C As Long, X As Long
R = 1: C = 2
X = 100
With ActiveDocument
With .InlineShapes(1)
If Not .OLEFormat Is Nothing Then
If Split(.OLEFormat.ClassType, ".")(0) = "Excel" Then
Set objOLE = .OLEFormat
objOLE.Activate
Set objXL = objOLE.Object
objXL.ActiveSheet.Cells(R, C).Value = X
On Error Resume Next
objOLE.Application.Quit
End If
End If
End With
End With
Set objXL = Nothing: Set objOLE = Nothing
Application.ScreenUpdating = True
End Sub