I DONT KNOW IF YOU KNOW OR NOT BUT THE 428 CRANK NEEDS TO HAVE AN EXTERNAL BALANCED DAMPNER AND FLYWHEEL OR FLEX PLATE. IF THE CRANK TURNS CLEAN FROM THE MACHINE SHOP IT WILL FIT FINE. BUT!!!!!!! YOU WILL NEED TO GET DIFFERENT PISTONS. THE EASIEST WOULD BE TO GET 410 PISTONS.(390 BLOCK WITH 428 CRANK)THE WRIST PIN HEIGHT IS DIFFERENT THEN THE 360,390 ONES.IF I UNDERSTAND MY BOOK I THINK THE BLOCK WAS MADE IN FEBURARY 5TH (1969?) DONT QUOTE ME THOUGH!! AS FOR THE DAMAGE ON THE BLOCK THE MACHINE SHOP WILL BE ABLE TO GIVE YOU A FOR SURE ANSWER.