That 2396 unit is for a 54 with automatic transmission. The 2403 was 55-63 all, and service replacement for 46-63. Should take a D306 cap (1924248), D105P points, and a D405 rotor. The 2305 uses the same cap, point set and rotor.
If you have a 57 block, get a 2403 distributor, have it rebuilt so it works properly.
Nice clean lubricated advance weights on nice tight solid pins, all clean, new components, check point tension and get it on to a sun machine or Allan machine to set the dwell and confirm the advance is coming in when it should and is all in when it should be.
