You could use an angle bracket inbetween the hole an the plate. Then use bolts to fix the bracket to the frame and to the plate.
You'd need to figure out what the threading is inside the hole but that's trial and error.
@Carabo started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
You could use an angle bracket inbetween the hole an the plate. Then use bolts to fix the bracket to the frame and to the plate.
You'd need to figure out what the threading is inside the hole but that's trial and error.