It all looks very nice! The shop at Innotech is looking good, I would love to visit again.
If you fill the holes with steel of some sort, the alternator will cog badly and assembly might become a nightmare ~ and ~ in running, it maybe hard to keep the stator out of the magnet rotors. If its powdered steel, or laminated steel somehow.... you will avoid most eddy current losses but no matter what you do it's going to cog badly. I would not do that with this sort of alternator design.
I'm not sure I'm keen on the use of tie wraps to hold the coils together either, It's probably just fine but it might add a thicker layer of resin between the surface of the stator and the coils and impede cooling (slightly). That is probably just nit-picky though I'm sure it will work fine.
Your posts might look better in the future if you can figure out how to post all your pictures in one post, not a big deal though.
Thanks!