I worked for Centerline for 12 years.
Centerline made the Auto Drag in 2 ways.
The one without the ridge is the original Auto Drag that was stamped out.
The one with the ridge is what they called the Auto Drag III
It was a 2 piece custom built wheel.
The only problem with you grinding or milling is if you don't do it right you ruin the wheels and you are stuck.
Best thing to do is get a hold of Wheel Ventiques and let them know what is going on.
They might have the correct wheels with the right center bore and be able to swap them out for...