Technical What kind of valve?

I have a old 4 I/8 x 3 3/8 flathead race motor from the 60's[I think] that I'm trying to rebuild. Valve size is 1.624-1.627 and length is about 4.845. These numbers may not be perfect but are close. I've had no luck in trying to find out what the valves are or what motor they may have come from. I know it's a shot in the dark but any ideas might help. Thanks, Pete
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The sbc 1.6" exhaust valves would be a possibility, as that's what is commonly used on flatheads today.

 

I tried one, went to deep in to the seat. Chevy over sized racing valve at 1.625 might end up being the deal. Just hoping to maybe find out what these are. Thank you. Pete