Agreed. You don't have to buy specialty arrow shafts. Get good quality standard shafts and learn to prep them, like the squaring you are referring too. I'd get a decent field point test kit and see what tunes.
Another problem I see all the time with folks building heavier arrows is immediately jumping to 250 or 200 spine arrow shafts. I look for the weakest spine shaft that will tune with a little margin for error. In my case 340 works great. That puts as much weight forward as possible in the system.
Take the spine your spine chart recommends. For anything over 125gr up front, Go one spine stiffer.
Or just go to that link(not you, anyone reading along who hasn’t yet) I posted.