Not to change topics here, but what is it that is motivating your switch to USS? Would it be more relaxing / comfortable perhaps?

Let me know how it turns out!

It's interesting, HP Velo is one of the few manufacturers who seems to offer either USS or OSS on it's bikes - is perhaps what makes the USS practical with direct steering is the relatively short distance between the steering axis and the seat? Or will yours have some sort of linkage? On a Bacchetta for instance, to get direct steering, it would take an awfully long set of handlebars and/or a long stem to get the bars back to near the seat...So a bar linkage would be the only good way to do it on a Bacchetta.