As ijimmy made mention of above it normally depends on several variables like point weight, shaft length, etc... I trust Pat's judgement so if the chart recommends it and it tunes well both in terms of paper and group then I would go with it instead of the 340. It seems to make sense if you are thinking of switching arrow brands anyway.

As a side-note, most bows shoot a slightly overspined arrow better than a slightly underspined one.