Grammatically it is correct. But I am not sure about what you mean. To me the sentence means "the eighth floor is around the south of the school" What would be the original meaning?

I think you are trying to say that the 8th building is around the south of the school,right? If so, you'd better say 八号楼/八栋在学校南边。 Or if the building is named as 八楼, your sentence is totally correct.

The eighth floor is around the south of the school, which seems awkward. Where are the first floor, the second floor... and the seventh floor? I suggest you say the eight-storied building is around the south of the school. 那棟八層樓房/ 那棟八層樓高的大樓在學校南邊.

thanks!~

八楼 means eighth floor so......this phrase doesn't make sense.