My advice at this point would be to pick up some factory loaded ammo in those weight classes with those projectiles and see how they cycle. If you have no chronograph, you can't be sure that you have enough power to cycle properly, but you have the right powder for that weight range. It may or may not be the most accurate load for your rifle, but you will find that out with more testing. My concern is cycling, and that powder is right for that. With 28.2c, ( compressed load), being shown as the max load for your combo, and 26.0 being the min, I would say that it would be cycling correctly as far as the load is concerned. Are you seeing swipes, flattened primers, cratered primers around the firing pin indentation, bulges just above the case head, extractor or ejector marks, etc.? The load data I put up there is from Hodgon, and is for saami chambers and 1/10 twist. You should be able to get a little more with the spec II chamber, but I would be sure that it is indeed a spec II seeing as how the previous owner did the work. You would have to be sure of his competency. If he had it done, I would personally like to see the receipts for the work if it were me.
Back to the ammo issue. I would recommend Palmetto State Armory, they have the SSA 115 gr Sierra for 18.95. I would also say get a box or two of something lighter, under 100gr to test for cycling.
Using an old formula for estimating velocity, you should be around 2560fps or so, which should be good pressure wise and cycle normally.