In general, the higher-end forks will have investment cast crowns and forged fork ends. Look for a weld seam on the bottom of the crown; if you find one it's not investment cast. Forged fork ends tend to be thicker than stamped ones, and usually have a manufacturer name stamped on the face. Post some pictures of the bottom of the crown and the fork ends if you're unsure. Here's the fork page from an early 80s Tange catalog:
