I wonder: could a type bar return spring be fitted somehow under the type guide, like on a Skyriter or Series 5? Just to give type bars a little kick on the return.
As a prototype, you could swap the type guide screws for longer ones and just stick the legs of the return spring in them. If it works, a prettier solution might be to machine two grooves on the back of the type guide to hold them in place with the pressure of the guide against the segment (just like the SC machines), using the original screws.