Stones or Carbide for valve work?

It's been a year but, sounds like you're gearing up for some serious valve work and porting. Both stones and carbide cutters have their pros and cons. Stones are great for initial shaping and can be more forgiving, but they wear out faster and might not give you the precision you need for fine work. Carbide cutters, on the other hand, last longer and provide a more consistent cut, which is crucial for porting work.
For more detailed insights and tips on valve work and tool selection, you might find this guide at Your Ultimate Rock Tumbling Guide helpful. It's a great resource for DIY enthusiasts like us diving into these projects. Best of luck with your valve work and porting adventures!