I'd also take some time and make sure its tuned up and running right as it sits right now. I have zero experience with non variated moby but it seems like with the SHA on there you should be able to get 30 out of it.
top speed should be pretty close to what it would be variated, but the acceleration wont be as good. you'd be surprised how much those worn out rubber motor mounts can kill performance, all that energy the engine is wasting shaking itself apart.
i'd dig around for a 'how to convert your 50L to 50V thread or wiki topic, i'm surprised someone hasn't done that, but off the top of my head i can't think of one.