As you are travelling in first I think it will be fine,
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I tried to edit my post above to say precisely that. You'll most likely be fine in Business Elite (Delta doesn't have international First). And if the connector on the 717 is domestic First you'd probably be okay too.
ScotlandScout, the dimensions you posted are for the carry on, not the personal item. I'm assuming the OP also has a carry on. But DL doesn't specify dimensions for the PI which allows for wiggle room - my "camera bag" is huge and wouldn't fit the UA personal item sizer, but it's a camera bag and so DL would have a hard time forcing me to check it (not that I'd risk having $2000 worth of camera plus lenses going on the hold).