Retro mountain bikes

That will fit you fine.

For retro mountain bikes it's always important to use retro sizing guidance, the most important tenet is "buy the largest size you can, you will grow into it".

I will always remember my childhood friend Olly, who at about 12 was a not-inconsiderable 5' 5 inches tall being given a 23" framed Claud Butler for Christmas, I don't think he ever did grow into it.

I have one and she should be fine, i am 5' 11" using a long saddle post and a 120mm stem so it should be ok for her