I think $100,000 is a nominal figure to reacquire and move an old MU car. As an LIRR historian/nerd, I would love to see one preserved and maintained. Operationally? This won't happen so drop that idea and shoot to a preservation plan for 2022. Find a building into which the cosmetically restored car will be installed. Plan a meaningful comparative display around it, such as "How has Long Island life changed between 1950 and today?"
Perhaps get OBRM to donate a simulator cab. Include displays for Sperry, Grumman, Republic, potato agriculture and shipping, the L.I.E. (with at least one Volkswagon "Beetle"....... Get where I'm going with this? The MU car needs to be included in an established museum or a planned and funded future museum.
I don't see any other way. I'd like to, but I don't.