You have to be really desperate to chain drill. At best, the cut is ragged and some sawing or filing may still be needed to complete the cut. To get the best possible results, each hole must be carefully placed so that you don't break through to the adjacent hole nor leave too much room. All of this take time.
I can't address how ugly the cut will be but can at least make the process much faster and more precise.
If you are interested, please see
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