She was mostly a movie star and did a few things on Radio...
Her HD releases are here:
https://www.blu-ray.com/Marilyn-Maxwell/101586/#Bluray
If you're a fan buy the discs and support her.
soulcity if it was me, I would probably get this release
https://www.blu-ray.com/movies/Wild-Wome...ay/217847/ as it was firstly in colour, also I really like the studio that released it they are very good. The sound is stereo. Also it was released not all that long ago, in 2018 in December. Yes it was a TV movie but she stars in it. It's not widescreen because of the year it was made but it's more like 4:3 format picture which is fair enough. Will look much better and sharper than youtube, if you like that one maybe consider getting another one at some point?
I'm not sure but maybe this one might be a good choice:
https://www.blu-ray.com/movies/Rock-A-By...ray/33967/
Again it is colour and it looks really good in the screenshots. For such an old movie they have done very well, I have releases from Olive Films. Only Mono sound, might be okay though, you get that old fashioned feel to the movie. I'm not sure if this one is a musical, maybe that's the sort of thing you're looking for if she is singing in the movie might be what you want?