all just my opinion but with new shooters I recommend over weighting the front a bit more and see what happens first so spin a 200 on there OR unscrew your 125 and then spin it back on thru a few washers or anything to get some weight we don't care if it sticks in we need to see the nock in flight,,, 45# wont snap a 2016 so see what it does but if he is plucking he needs to fix that first. draw back with the string barely on your fingers where it feels like its going to slip off,,, hold bow perfectly vertical and relax hand to shoot, do not move the bow hand at all,,, forget about accuracy just watch the arrow.
out of the gate though I would spin on a 175 and work up from there... I have a 48# ST Charles Tbird with a Dacron string and I use 200gr + insert on 1916's that are 2" longer than my normal BOP,, they don't even need fletching out to 20yds..