We see that it is the same bike as was originally posted. There are a few pictures of the green & red or red & green Excelsior bicycles on this site; such as thread # 12768 — and the Sears Elgin labeled Excelsior-built bicycles are mostly red.
What to do with a bicycle that is already gone — and exactly how far gone is too far gone?
It is your bike; and there are many 1920’s Excelsiors (or Sears Elgins) still out there. Many a big-wallet member might pass on a bike project like this one — and wait for a more minty example.
You might first try the minimal clean up and lube actions to see if a rusty old bike is the right style for you; maybe, after a while, you might get used to it?