If you are not comfortable with cutting your own columns to height Worthington Millwork can always cut the columns for you.
Instructions: Preparing to Cut the Fiberglass Column
Note: Cut from the bottom of the column when using tapered columns.
Place the column on its side and brace it for stability. Measure to the desired length and mark the column at the cut line.
Apply a layer of low-tack masking tape around the column at cutting length in order to protect the cut edge from being chipped by the saw blade. Take a moment to put on protective eye gear.
Fire up your circular saw with an abrasive and fine-toothed blade and make the cut through the masking tape, rotating the column as needed too complete the cut. If the column is tapered, make sure to cut only from the bottom in order to keep the aesthetic and proportion of the column.
Remove the cut portion and the masking tape from the cut end and install it.