For starters I hope you meant $? and not $_ >> 8 in your second code snippet. You could wrap that bit shift any way you like such as

$rc = sub { $? >> 8 };

# one way
system(@mysyscall) and die "@mysyscall returned ", &$rc;
# or
if (system(@mysyscall)) { die "@mysyscall returned ", &$rc };
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But of course TIMTOWTDI!

Update:BTW: Welcome to the Monastery.
I can't believe it's not psellchecked