you would be much better off drilling those flange holes out to 10MM and using the  larger stronger  bolts  and they should fit  the disc http://www.marlincrawler.com/htm/axles.htm

i might do that for right now i went and got some grade 8 5/16 bolts to bolt it up.i also had to put a washer between the front pad and the bushing that goes in between the pads because it was so tight it would not allow the wheels to spin