Jeff what you want to do is pretty simple and I don’t understand why you have messed it with command line iptables.
In ZS web gui go Network->Router->NAT and enable ETH00
Network->Router->Virtual Server add a rule INPUT INTERFACE=ETH00, IP ADDRESS=ANY. PROTOCOL=TCP, LOCAL PORT=80, REMOTE IP=192.168.254.200, REMOTE PORT=80 and click the + button.