GLASS BEADING INSIDE OF VALVE COVERS AND OIL PANS

Oil pan is ok in my opinion, you have full access to clean out any blast media residue after blasting. Valve covers are a bit trickier. I agree that the baffle in the valve covers is a natural trap for blast media residue and would nor use an abrasive media. Soda blasting is safe but won’t do anything against rust. I have degreased and then soaked in evapo-rust with good results.