Which super twin 6hp? Here is a link to some instruction scans of my wd4s motor that is a 1946 6HP model. http://pub9.bravenet.com/forum/static/show.php?usernum=737212788&frmid=52&msgid=715480&cmd=show
It lists the knob settings, but doesn't show float level. I would just set the float so it looks level if you can't find it elsewhere and make sure it is not waterlogged or has a hole.