If you treat kilo of ore with AR, and assuming that you leached the gold out, there comes the question - how much of the gold could actually be there ?
Regular ores yield below 1ozt/ton, that means one kilo of ore will contain at best 30 mg of gold. IF you leached all of it, say with 1L of AR, now you have solution of 0,03gAu per liter. And here comes the problem - in this low concentration, stannous will usually show nothing.
Cementation should give you some precipitate to work with. Only if you dissolve this precipitate in AR once again and test this solution with stannous, you will obtain relatively reliable result.
BTW, what is approximate purity of the gold in the ore ? I am asking because if you have high silver content in it (say 60-70% Au, rest silver), dissolution in dilute AR would be very slow and leaching efficiency minimal.
Acids on rocks isn´t a good technique. If there is freemill gold in the ore, there is no point in acid treatment. It is dangerous and wasteful, inefficient, simultaneously creating much more hazardous waste than mechanical separations.