A loose bolt fit through the prop is ok. Better than a tight fit by a bunch. Yes, you will have to drill the back plate. If your spinner has side screws holding the cone in place take your time and be very certain about prop alignment in the spinner cut out before you do this. The easy way is to drill the prop with the holes in the position you desire, then set the prop over the spinner back plate, bolt the prop to the back plate, and use the prop as a drill guide. Use a 10mm bolt and nut to secure the pair for drilling.