Not really standard. Just measure the hole for the compass and get a direct replacement (i.e. Ritchie for Ritchie) and set it. Others also may fit, but it's better to have exact measurements. The compass box should tell you what size hole is required.
+1 to what Fireman said...I had to replace my compass with a direct replacement (same model #). I still had to enlarge the hole in order to fit the direct replacement...take the measurements with you.