He mentioned that he pushed the clutch in with no luck in the first post which is normally the easy button like you mentioned.
With what has been tried and only 1/4” left I would be suspecting an install issue with the clutch plate as well. All my experience tells me the input shaft goes into the pilot bearing more than 1/4” so I would think the input shaft has already started into the pilot bearing and is hung up somewhere else.
Be sure to measure the ID of the hole in the bell housing and the OD of the input shaft retainer for the transmission. Could be an interference issue there.