Been awhile since we ran 305's and had to deal with that, but I think we had Sanders or MPD castings, where we only had to slightly clearance the little bosses inside the casting behind the motor plate fasteners. It just has to not hit when it spins inside. The crank will cut it if it needs to, but obviously you try to avoid that. I have seen the buckley yokes break the big studs that bolt to the motorplate before on a rough track also, but do whatever you feel like. Keep in mind if you go with a ball and casting, use one manufacturer for the ball, casting, and torque tube. Different companies use slightly different tolerances, so you can wind up with a very tight torque ball, or one that's very sloppy. Good luck!