Four of the inlet valves on my Chevy 383 have scratches on the stem perpendicular to the length - I am worried about them causing stress risers and snapping the valve with disastrous consequences. The scratches are just deep enough to see & feel with a finger nail but would polish out with minor thinning of the stem (Certainly less than the thinned part in the throat which is 0.333" just above the foot.

They are Stainless steel valves 2.02" diameter with 0.34" diam stems. The polished part will not enter the guides. Buying new valves will delay the project by 5 or 6 weeks and cost quiet a lot - polishing out the scratches on the stems will take a morning on the lathe - what would you advise?

I think the scratches happened when the valve spring dampers broke. The valves are straight.

A couple of caveat;

1) you say the scratches are shallow but are the edges smooth with no lumps of metal 'galled' up along the edge?
2) how deep, as a percentage of the stem diameter, are these scratches?

If they are smooth edged, less than 2% in depth and the scratches run along the length of the stem and not around the stem - I would re-fit them and forget about the issue.