Hi,
I think this design is flawed.
You should not have constructor take responsibility for such conversion. Ideally the class's contract should specify it to be clients responsibility and you should have validation logic to ensure that data in min and hrs are within allowable limits.
If at all you want then you can expose a utility method which can handle such conversion. e.g int evaluateHours(int minutes). Similarly for hours.
Hope it helps.
Thanks,
Satish