This concept idea would most probably have been developed into a long Scrooge McDuck adventure story (24-36 pages) as Barks also indicates by writing SCROOGE O/S (one-shot) in the header.
main plot is that of Scrooge being unable to collect more money
from this world, so he travels out in space - with Donald and the
nephews - to collect more from other civilizations! He is helped
by a strange scientist, who turns out to be an alien from another
planet. Soon Scrooge becomes fabulously rich in Planet Z money.
Barks made a similar plot draft, in which Scrooge tries to hide his money from the Beagle Boys on the Moon. Again, a strange scientist turns out to be an alien who flies Scrooge, Donald, and the nephews to his home planet - this time called Planet X - where 'the ducks have adventures' as Barks puts it.