The high soil pH (8.2) is probably going to be the first thing you need to address since a high pH can cause many of the surplus minerals to be more available than if the pH was in the 6.8 range.
Getting the pH down into the high to mid 6's can take care of the calcium excess and it might even bring the P up into an acceptable level.
So, grow a diverse cover crop set, like buckwheat, clover, peas, etc. (even simply using a
deer feed plot seed mix will do wonders) and work on getting some sulfur into the soil to bring the pH down (do this in small increments, not one big dump of sulfur).
Since you have some native grasses growing there already, it would be easiest to add more plants and let their exudates do a lot of the adjusting for you. Then you can start with some small quantity amendment materials so you don't overshoot the goal pH wise.
As your pH comes down more fungi will move in and begin to thrive along with more of the bacteria species we really want in our soil.
Both of these will also act upon the soil minerals and from that point you can better make adjustments if necessary because you have built the microbiome first.
Redhawk