I'm not so sure that this approach will give you the answer you are looking for but it is worth a try. Here goes: The three sabot slugs my H&R Ultraslug shoots best are (1) the 3 inch untipped Federal Barnes Expander, (2) the 3 inch Remington Copper Solid, and (3) the 2 3/4 inch Lightfield Exp slugs - in that order. I would not hesitate to use any of these sabot slugs because my Ultraslug shoots them all pretty well. Remember that if you sight your gun in for one slug, it doesn't mean you can switch to a different slug and still be sighted in. I have exactly the same combination you have i.e. Ultraslug topped with a Nikon Slughunter scope and they are a match made in heaven. You won't regret getting that combo . . . I know I sure don't!

One piece of advice: if you are going to be taking shots at over 75 yds, get yourself a good rangefinder. More people miss or wound deer every season because the misjudge distance or crosswind speed than all other reasons combined. I was amazed at how far off my distance judgment was when I first got my rangefinder. Last season I took a 7-point at a ranged 147 yds by using the 150 yd aim point on the BDC reticule. Before using the rangefinder I had guessed that deer to be close to 200 yds away. Lucky for me it was dead calm and just after daylight because at 147 yds, even a 10 mph crosswind can affect your slug more than you realize. I have learned that if the crosswind speed is more than a few MPH to keep my shots to 100 yds or less because I can judge the impact the wind will have on my slug better at shorter distances.