Hard to say, but to me that is not minor. "Minor" on a race bike is a bar slap on the top-tube from a fall. One that is not creased, and has not disturbed the paint. Something like that does not bother me too much, and one of my favorite bikes has one.

What you have there should be repaired professionaly, and would require re-painting the frame after (or at least re-painting the top tube and matching the patina if you can find a shop that would do that). And that's where a huge difference in value is . Original bikes are worth far more than refinished ones.

But it depends on the buyer. The right person may want to take that on as a project and pay well for it. The larger size may work to your advantage as well. 62cm Masi's are probably not that common and two buyers may fight over it. To me it would be worth 40-50% less than the exact same condition bike without the damage, but who knows what will happen in a live auction.