Date and authenticate Challenger Eaastern Board

Hi all, I was given this board (thrown out as junk) and I thought it would be cool to hang on the wall or possibly restore if it is worth it. I’ve been reading the history of Challenger Eastern and would like to try and date this board and authenticate it. Any help would be much appreciated. It is 6’8”.

See if you can get us a pic of the bottom and fin configuration. I am sure that will help.