At the very least, you would want to see if the connectors on the new display match up with those on the bike. Otherwise, you'll be up for quite a project, that could easily be a total re-wire, and likely include a new controller.
I wasn't real keen on Rad's display either. One thing led to another for me, and I ended up installing an entire "conversion kit" that included ALL of the electrical and electronics, including a bigger drive motor. I was working on a bike w/direct drive hub though.