Ideally the OP should re-square the dropouts, but it isn't critical if spreading the frame 6mm (total) or less.
That much change in angle is barely discernible with the more common drop out alignment gauges. It's probably about as close as the bulk of the bikes sold new.
Reminder to the OP. You didn't say, but if this is not a steel frame, it's 100% a no go. Otherwise, it's almost too easy, (I've done dozens) and there's not much that can go wrong.
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