Changing the designation of a "rifle" receiver to "other"?

A friend has a receiver he’s been sitting on for a while and want’s to move. I thought about picking it up as a base for a pistol build. The only issue is that it was identified on the 4473 as a rifle (yes, everyone involves knows that was an error). It has never been assembled as a rifle. It’ll go FFL to FFL if I get it so I’ll have to do a background check on it anyway. I was wondering if I could have it listed as an other at that time, or would the original 4473 control.

If your FFL receives it as anything other than a receiver than he’s wrong.

Thank you.