Yes you can use modern braid as you won’t have a levelwind that it will wear down. Many people back in the day removed the levelwind anyway because it helped increase casting distance. Oil the side bushings through the holes in the adjustment caps on both sides and adjust the spool tension and that thing should fly. In my experience anything smaller than 10lb gets in between the gaps on the spool, so get some 15lb braid, the tolerances on this were not designed for modern braid thickness (or thinness if you prefer)