Finishing details of basement stair project

[Don Meinke]

Doorway landing and retaining wall concrete portion finished.  NOW trying to determine if 3/8 plywood would be strong enough IF screwed to back of 2 bye treads for added rigidity???

Headroom is at a premium here too.  Already moved landing back and removed a forward header.  I am 5'10'or so and have several inches above that as additional space.  SO it would take OVER 6 foot tall person to hit head,,,would the 'expect' to duck under in OLD house,OLD basement??? Could cut another 3 to 4 inches out above,,more than that would require extensive floor wall reno and a notch out of dining room floor/wall.  Is it worth all that.

OLD stairs were pretty much a ladder effect,5 inch tread on 8 inch rise.  New are 7.3" rise on 10 inch tread,,,much better.  No way to get to legal code,,,too narrow,,, too short on headroom...Aim was to make "better" and it has,,,greatly.

Been wanting to do this bucket list improvement for 35 years,,,finally had the brainstorm to design and DO it!!!