Hi MugenB.
That one is really old motor-that balancing on cranck was popular because on that time idea was that cuts which we have now on cranck will increase case volume, so everybody was making those cuts and some times even put sleeve over it to cover cuts. But later it was proven that web regardless the shape at rotating in our RPM is concidered as full round body, so after it was proven, everybody switched to DELTA type ( or alomost everybody ).
As far as engine-pics are really not focused, but for sure what I will do is make the cuts which going from transfer ports to booster-it will be firstTo make sure mixture passage is good to all ports, second I will do is to make chamfer on induction hole ( or you can make turbo scoop). Will make sure that booster angle is at list 45 degrees.
Try to make please more focused pics of the side of sleeve where we can see transfer ports and booster.