excel vba defining range with specialcells

I am building a procedure that creates a new workbook, looks up excel input files and copies/formats them in the new workbook.  I want make my code dynamic so it can adjust to varying cell ranges to copy and paste.  

In my attached code, line 330, I would like to replace "A834" with a dynamic reference to the cell.
How can I do this?

'copy whole sheet
    Sheets("OH Count Collateral").Select
    Cells.Select
    Selection.Copy
    
    'paste in OH Count sheet
    Sheets("OH Count").Select
    Range("A1").Select
    ActiveSheet.Paste
    
    'figure out where the data ends for the next paste
    Range("A1").Select
    Selection.End(xlDown).Select
    Range("A834").Select
    
    'copy the next sheet
    Sheets("OH Count Pool").Select
    Range("A1").Select
    ' use the SpecialCells method to select only cells with data
    Range(Selection, ActiveCell.SpecialCells(xlLastCell)).Select
    Application.CutCopyMode = False
    Selection.Copy
    
    'paste into OH Count below the data from the first copy/paste
    Sheets("OH Count").Select
    ActiveSheet.Paste

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