Can I bind a virtual server port to real server port via iRule for every connection

I assume 2 bytes referred is in TCP payload.

Try this:

when CLIENT_ACCEPTED {
    TCP::collect
}
when CLIENT_DATA {
   set port [TCP::payload 2]
   TCP::release
}
when LB_SELECTED {
  node [LB::server addr] $port
  LB::reselect
}