Measuring by volume seems to be the norm for both your gun and your Gold 3f powder choice. Here is a chart that shows weight to volume for various powders.
http://www.curtrich.com/BPConversionSheet.htm
It shows that 100 gr volume of Gold 3f is 83 grains weight. So, multiply your chosen volume load by 83% to get to the weight that goes with it.
American Pioneer shows 1823 fps, for 240 grain bullet with 100 gr. volume Gold 3f. Equivalent energy at 300 grains is 1631 fps. I'd expect the 300 gr bullet to be about 4% higher than that, maybe 1690 fps. This is in your 1500 - 1700 range. This is 83 gr. powder weight, so your 80 gr. weight starting point seems good.
Starting with your volume measure around 95 grains (96.4) will be similar. If your goal is improved consistency, it may be easier to work up an accurate volume load, then convert to weight. Maybe it will be more consistent? Let us know the results.