Hi: One way to rewire the stator is to wind alternating direction coils. Wind coil 1, phase 1 from slot 1 to slot 4 cw, then wind coil 2 phase 1 ccw from slot 4 (the same slot that coil 1 ended in) to slot 7, continuing all the way around the stator until the last coil ends in the same slot ( 1) that coil one started in. As you go around you are skipping two slots for each coil. If you use wooden dowels in slots 2 and 3, 5 and 6, etc it's helps you remember what you are doing and makes the coils uniform. Wind phase 2 in the same way slots 2 to 5, etc skipping 2 slots and ending up in slot 2. Then wind phase 3 in the only remaining slots. Remember to alternate the coil winding direction. Cw, ccw etc.
Also as you finish each phase use you thumbs to push the coil ends to the outside to get all the coils in. But still leave room to get the case on.
Hook all 3 starts together and use the 3 finish wires as your 3 phase output. But if when measuring the open output one phase is lower than the other two hook the starts of 1 and 3 and the finish of phase two as your star (wye) connection.
Higher frequency is better for any alternator. Alternate the 12 magnets north south, north south etc.
Arch. Ps the magnets size should fit in the hole of a coil. For example it should be smaller than the distance between slots 1 and 3 by half a slot.