Input box to needs different type of variable type (RC vs. A1?)

I'm trying to use an input box to prompt the user to select the row containing the data they want plotted. I am having a problem with the way VBA likes to have its rows and column references formatted (as a letter?) vs. what is returned from selecting an active cell (as a number?).

Here's the example data that applies:

Book1.xlsx

The portion of the code I'm having trouble with comes just after the first If statement.

Sub MakeFigures()

    Dim intFirstRow As Integer      ' First row of the current chart series
    Dim intLastRow As Integer       ' Last row of the current chart series
    Dim intStartRow As Integer      ' First row of data in the spreadsheet
    Dim intRow As Integer           ' Current row being processed
    Dim strBH As String             ' Current monitoring well
    Dim strDataColumn As Integer
    Dim xlChart As Chart
    Dim xlsheet As Worksheet
    Dim Parameter1 As Range         ' Column containing 1st parameter chosen by user to plot

    ' First select a chart
    If ActiveChart Is Nothing Then
        MsgBox "Please select the empty chart tab before running the macro.", , "No Chart Selected"
        Exit Sub
    End If
    
    '   Hard-coded chart, sheet, row and column selections here could be replaced by prompts to the user
    Set xlsheet = ActiveWorkbook.Sheets("Data")
    Set xlChart = ActiveChart
    intStartRow = 3    ' First row with data in it
    Parameter1 = Application.InputBox(Prompt:="Select the cell containing the name of the parameter you want to plot.", Default:="Navigate to your data and select the header cell for the data of interest.", Type:=8)
    strDataColumn = Parameter1      ' User's first parameter selection to be plotted
    
    '   Start in the first data row
    intRow = intStartRow
    strBH = xlsheet.Cells(intRow, 1).Value
    intFirstRow = intRow
    
    Do
        '   Step down the rows
        '   Is this a new borehole number? If so, create a chart series for the previous rows.
        If xlsheet.Cells(intRow, 1).Value <> strBH Then
            intLastRow = intRow - 1             ' The series ends at the row we just passed
            With xlChart
                Dim s As Series
                .SeriesCollection.NewSeries
                Dim intSeries As Integer
                intSeries = .SeriesCollection.Count
                Set s = .SeriesCollection(intSeries)
                s.Name = RangeAddress(xlsheet, "A", intFirstRow)        ' Set the series name to the monitoring well number
                s.XValues = RangeAddress(xlsheet, "B", intFirstRow, intLastRow) ' Set x values to the date column
                s.Values = RangeAddress(xlsheet, strDataColumn, intFirstRow, intLastRow)  ' Set y values to the data column
            End With
            
            '   Reset to start a new series for the next hole
            intFirstRow = intRow
            strBH = xlsheet.Cells(intRow, 1).Value
        End If
        
        '   Now move down one row
        intRow = intRow + 1

        ' Stop at the first row with no date
    Loop Until strBH = ""
    
    MsgBox "Chart completed!", , "Done"

End Sub

Private Function RangeAddress(xlsheet As Worksheet, strColumn As String, intFirstRow As Integer, Optional intLastRow As Integer) As String
    '   Returns a cell address or range address suitable for input to the x or y values
    '   property of a chart series.
    
    RangeAddress = "=" & xlsheet.Name & "!$" & strColumn & "$" & intFirstRow
    If intLastRow > 0 Then RangeAddress = RangeAddress & ":$" & strColumn & "$" & intLastRow

End Function