Changing the field format of a custom time attribute

Summary

Changing the field format of a custom time attribute

Content

Hi All,

Require your suggestion on the best option to use when changing the field format for a custom time attribute.

There is  a custom attribute that was earlier a 'Character' format and now I need to change it to 'Number'.

Will it be a better option to create a number type value set and create a new custom time attribute/time entry layout component and associate it with the newly created numeric value set 

OR

Can I create a new numeric value set and associate it with existing custom time attribute and time entry layout component, will it cause any issue in the existing setup/processing? We have a custom interface using the values from custom time attribute, by using the existing time attribute we will be able to avoid any changes to the interface.