It is not possible to drill out a 10-24 hole and rethread it for a 6mm fastener. The problem is a major diameter, minor diameter conflict issue. The next size up fastener needs a thread that uses a tap drill which will entirely clean up the hole, when properly sized for the new fastener, prior to tapping the new thread. Your situation does not provide you this opportunity.
You have several options available to you without changing to another wheel;
- Use a larger fastener,
- Offset the steering wheel hub by 3 or 4 splines (if it is not keyed) and drill the hub for 6mm fasteners,
- If it is keyed then you need to make a new hub,
- Learn to love the old steering wheel.
Putting 6mm hardware into 10-24 holes is asking for a mechanical failure.
Ed