Howard Da Silva survived the blacklisting era.
The number has now been restored. I highly recommend seeing the movie and I also highly recommend listening to the director's commentary on the DVD. It's one of the best, most informative commentaries I've heard. I learned about Nixon's removal of that musical number from the director's commentary.
1776 also had an Oscar-nomination worthy performance from William Daniels. I think it was good enough for a Best Picture nomination. But another excellent and very innovative adaptation of a Broadway musical drama came out that same year, 1972, and got top Oscar attention -- Cabaret starring Liza Minnelli (Best Actress), Joel Grey (Best Supporting Actor) and directed by Bob Fosse (Best Director). Cabaret was in the Best Picture race. The Godfather was the winner. 1776 got one Oscar nomination -- for Best Cinematography.
What moves me about this musical is how vividly it brings the Founding Fathers and their task to life. These were men on new geographical and political territory. The American Revolution was underway. George Washington and his troops were in battle. Mothers were losing their sons. Those men who signed the Declaration of Independence were not men who lived in gated communities in homes with manicured lawns, electricity, indoor plumbing, telephones, cars and other conveniences. They wrestled with the problem of slavery, the profitable ownership of black people. That's highlighted in the strong "Molasses and Rum" number sung by John Cullum. (Another Broadway musical veteran, he would also go on to TV success as a member of the Northern Exposure cast.)
If you like musicals, give this patriotic production a look. Happy 4th of July.