Should his appeal be successful the Croatian striker is expected to seal a four-year deal after a fee reported to be around £6million was agreed with Hajduk Split.
Allardyce told the Lancashire Telegraph: "We will put up a very good case of course. He should be allowed to come and express his abilities in this country and show what he can do.
"He has a terrific goalscoring record. He is only 21 and scores one goal every 1.6 games. That is why we have forked out as much money as we have."