As was shown to me in another forum there is a way to get the uncompressed size of the gz file by viewing the last 4 bytes of the gz file.
Here is a piece of code that will do this
<?php
$FileRead = 'SomeText.txt';
$FileOpen = fopen($FileRead, "rb");
fseek($FileOpen, -4, SEEK_END);
$buf = fread($FileOpen, 4);
$GZFileSize = end(unpack("V", $buf));
fclose($FileOpen);
$HandleRead = gzopen($FileRead, "rb");
$ContentRead = gzread($HandleRead, $GZFileSize);
?>
This will read the last 4 bytes of the gz file and use it as the file int for the gzread.
Thanks to stereofrog for helping me with this code.