In general we do not recommend making edits to the Solution Packs since they are designed, engineered and tested to be working in the state that you download them in. If you need to make these edits you should first backup the pages before making any edits.
I think it would be best to use text inputs instead of the select lists like you mentioned. To do this you can just add a new text field to the form next to the select list, then just make sure to name the new input after the select list. If they have the same name and id the validations should still work properly. The only thing is that you would need to bind the validation value from the bindings tab back to this text field.