Lock plates can be an issue, especially in high torque applications (like the dreaded rear axle nut). However, the flywheel bolt torque is only 40 ft/lbs. I think you would be fine with keeping the lock plate. Rather than ordering one in, you could just cut one out from metal sheet. K350K’s suggestions are on the money as well. Lastly you can drill the bolts for lock wire, use hardened washers and loctite. It’s what I would do if I was racing.
What did I do? Can’t really remember. I would guess a new lock plate and loctite as well.