I decided not to use standard M8 bolts... I got nervous that there might not be full thread engagement with varied thickness of bus bars, and going into soft copper and aluminum terminal... I decided on using 30mm set screws to be sure they bottom out and use all the available threads. After installation, I'd say that it would be POSSIBLE to go with 25mm long sets screws 'next time' to have less extra stud sticking up if desired. There would be almost nothing extra on the connections with the cable lugs though. Probably best to use 30mm long studs.