Thanks! I got is working on a variant of that, I had to do some dereferencing and re-vectorizing, but it worked! Final snippet:

        my $vect1 = [ @{ $val1 }[3..5] ];
        my $vect2 = [ @{ $val2 }[3..5] ];
        my $norm = [ @{ $val1 }[0..2] ];
        my $varvec1 = V( @$vect1 );
        my $varvec2 = V( @$vect2 );
        my $varnorm = V( @$norm );
        my $nvect1 = $varvec1 - $varnorm ;
        my $nvect2 = $varvec2 - $varnorm ;
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