The Heritage 90 with a 175 point will shoot like a laser. The Heritage 75 with a 125 will impress you if you would like to go a little lighter on point weight. According to the math the Heritage 75 cut to 28 ½ would be the correct spine for a 125 point with your set up.
Take the advice of Dalebow and don’t start messing with weighted brass inserts. With some manufactures the thinking is they can produce one or two shafts that will work with all poundage bows. You can go that route if you want your arrow so front heavy it drops slam out of site at 20 yards and add an additional cost for the inserts or about another 10 to 12 bucks a dozen.
There should be no need for them if you have the correct spine to start with. Leave them full length and cut them back until you get the desired results using the point weigh you like.