If you're getting good results with 72v on 33 I'd be inclined to leave it there. 72v may be low (in terms of all electronic speed control with the SDS) for 45. Based on this:
http://db.audioasylum.com/mhtml/m.html?forum=vinyl&n=974466&highlight=variac+blake&search_url=%2Fcgi%2Fsearch.mpl%3Fsearchtext%3Dgarrard%2Bzero%2B100%26SelectForumvinyl%3Dvinyl%26SelectForumvinyl%3Dvinyl
I would try 72 and 92 respectively.
http://db.audioasylum.com/mhtml/m.html?forum=vinyl&n=974466&highlight=variac+blake&search_url=%2Fcgi%2Fsearch.mpl%3Fsearchtext%3Dgarrard%2Bzero%2B100%26SelectForumvinyl%3Dvinyl%26SelectForumvinyl%3Dvinyl
I would try 72 and 92 respectively.