I keep Ca levels in our 120g mixed BTA, zoo, lps and sps tank at about 420 ppm and I think your Ca is just a bit high. You should also be measuring magnesium to keep the alk, Ca and Mg levels balanced.
I use the underwater epoxy for mounting corals onto LR. It's the two part white stuff with green as an outside coating. Mix it really well until the colour is consistent. It's good for about 20 minutes, then it's too hard to mold after that.
HTH
