Short answer: no. Not ok. There are plenty of other songs to sing.

Longer answer: can depend on motive and context as well as content. Songs using racist language in the course of mocking/satirising/ridiculing racism can be powerful. I would consider singing such songs - cautiously.

I can't imagine ever singing a song with racist content for any reason without making my position on the matter very clear before doing the song.

Possibly singing something traditional but nasty to illustrate conditions and attitudes of the past. That could work, but would need careful handling.

To sing racist songs for amusement, or to pander to a racist audience, is in no measure excused by saying "but they're traditional songs".

I would also do the word-change thing if it seemed appropriate. In that case I may well tell the audience about the change and my reason for making it.