symbols and notes in early music

I would like to use some auld types of notes such as "longa" and "maxima" (rectangular white notes equivalent to 8 and 16 crotchets, respectively), on top of rhombic crochet, quaver and minim, for writing sheet music for early music. They do not require anything new in the function or technical feature, but only some addition to the present set of note symbols, this would hence be relatively easy to integrate, I suppose.