Probably your best bet with Schwinns is the tall Varsity frames, I think they're 24"seat tube. There's also a King Size American model w/a cantilever frame, but it was only made a couple years and hard to find.
I know of only one person that is that tall and she collects and rides the old large diamond frame Schwinn lightweights. Not sure if that's your cup of tea but there are some very tall lightweight frames.
That depends on how much leg extension you want and your inseam length.
King size middleweight frames are bigger, but not by much. Not nearly enough to make a difference for someone your height.
Tall frame 20 inch pre war are the biggest I've found, but barley big enough.
I have a 36 inseam and ideally like having the right seat height. I can get good leg extension with 20 inch pre war frame &18 inch long seat post. But then the handle bars are still pretty low unless you start to play around with taller rise bars. Long stems will only put the bars even closer so be mindful of that.
As far as strength you cant go wrong with most any of these vintage bikes, they are so over built you could probably melt one frame down and make two that would be plenty strong.
Unless you start searching out early 80's MTB's & newer, vintage ballon bikes are hard to fit to taller people and end up looking kinda silly when
set up for tall people.
This may be heresy here but I’ll throw it out anyway; maybe use a modern 29” Schwinn Gammon frame. It may not be solid enough for a real bomber run but you’re changing out all the other parts anyway so probably ok for general riding. The tough part would be finding a blade style fork for a 29” frame if you want to ditch the unicrown.