Stairwair rebuild - Spindle attachment

See ABPW for shot of old stair.
I am rebuilding a stairway and I am looking for ideas of how to attach new spindles to new stair treads and to the original banister.
I am inclined to miter on the end of the stair tread as in the original as it shows side grain and extends beyond the tread on the right-hand end. This is tricky as it is a side to end grain joint. I plan in splining it together and just gluing the forward end, allowing the back (right in this view) side of the end to float.
I would appreciate any thoughts on this part.
The current spindles are beveled and butted up against the underside of the banister and toe-nailed.
My plan is to bevel and but the new spindles, but to toe-screw them, with a finish (small head) screw. I think boring holes in the underside of the banister might be really tricky. I would be really screwed if the holes did not end up directly over the mortises/screwholes on the bottom
The bottom is where I'm waffling. If it use a double-ended screw (I'm not sure what they are called) I will get superior resistance to pulling, but it will make it tough to prebevel the top, as I will only bottom out the screw(s) at a particular rotational orientation.
The other option would be to cut square mortises as in the original, but screw them into the endgrain of the main oak stairtread to secure them.
Or a different approach:
1. before assembly, mark the exact position of the tops of the old spindles on the banister. 2. install new treads 3. bore holes in the underside of the banister 4. install banister 5. Mark screw holes on new treads with a plumb bob 6. Remove banister 7. Install new spindles with double-screws 8. Install banister onto spindles
Any alternative ideas or thoughts on these approaches would be appreciated.

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