First of all: there is one big error in your question: there is no "LotusScript- field" in Lotus Notes. All editable fields have LotusScript- Events, but the main language for fields is Formula. With formula you can define Default- Values, Input- Validations and -this is important for your question- Input- Translations. The Input- Translation- Event can contain formulas to transform the content of the field before storing it.
Of course you can write these 10 lines of code in QuerySave. But you can also just put this formula in the input translation of the field:
@Ascii( @ThisValue )
It's your decision...