Would the following be a vague step in the right direction?

my @assignList = qw(camshaft gearbox drivetrain smokestack junkyard);
@{$big_foo_bucket}[@assignList]=@other_foo_bucket[@assignList];
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Still not ideal, but the assignment of the list at least removes the problem of keeping the two in order. I suppose where you want to copy all of the elements of %other_foo_bucket you could have simply assigned @assignList=keys %other_foo_bucket; and it'd happily leave any items in %big_foo_bucket which aren't in %other_foo_bucket alone.