A Text::CSV solution:

use strict;
use warnings;

use Text::CSV;
use Test::More tests => 2;

my $in   = '23 45.67 "John Marcus" Surname';
my $want = [23, 45.67, 'John Marcus', 'Surname'];

my $csv  = Text::CSV->new ({sep_char => ' '});

ok $csv->parse ($in), 'Parsing';
is_deeply [$csv->fields], $want, 'Fields match';
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You will probably want to extend the tests to better reflect your real-world requirements.