As far as I can tell WinTAR writes standard tar archives..the key thing being of course that it looks like they are written as such straight onto the floppy as if it were a raw block device rather than being written to a file on the floppy filesystem.
I am guessing here but I would have expected that dd'ing the floppy into a file and then using tar to extract from that would work.
so dd if=/dev/fd0 of=floppy1.tar
substitute the device node for whatever the floppy device is on your system...you don't mention if you are using the original SCSI floppy drive or not.
Set the write protect tab on the floppies so that no silly mistakes can be made..naturally
What did you do so wrong that your punishment is to extract data from 500 floppies...must have been pretty bad :-)