commando rear wheel security bolt rim lock

Hello I have read that many do not bother with the security bolt with modern tyres but I wish to fit one to my 1973 850 commando rear does anyone know its location [ for drilling the new rim] in relation to the tube valve hole , is it opposite ?a third way round ?so balance can be bettered with wheel balance weights at that point, if anybody has a original commando wheel could they let me know, I know wheel balance is not as critical on the rear as the front but would like it as good as possible . I bought a 1974 850ccnew and that had the security bolt fitted I am sure. thanks in anticipation.