I really wish people wouldn't talk down to someone who disagrees with them. I've read the rules, and i just think you're wrong about RAW.Very mixed responses.
RAW it seems to be a yes though as an upcast spell is aspell of that level.
As mentioned earlier.
Reread the rules.
Cure wounds is an artificer spell. Infused item qualifier.
Upcasting it makes it a level 3 spell.
RAW you can stick it in an item it seems.
Spell Storing Item does not have 3rd level spell slots- not only does it has daily uses, but you can cast an equal number of second level spells as you can 3rd level spells. As such, it falls under Casting Without Slots, as per Chapter 7 of the PHB. As such, there's no way for "the spell expands to fill the slot it is put into." (PHB, ch7, "Using a Higher Level Spell Slot")
Therefore, we default to the spell level printed in the spell description for these slot-less spell casts.