The only way that you can get acceptable re-scaling of menus is to go from BR to DVD, and do the editing in Photoshop. Simply re-scaling the menu here will not give acceptable results.
I usually copy the various button layers from the BR menu to a new DVD menu file created using the provided Photoshop preset. You will still have to do some manual re-scaling and alignment. The thing that has given me the most trouble over the years is round button highlights - a segment is often chopped off. Font sizes will probably need adjusting too.
Unless you are adept with handling layers and groups within Photoshop, it may be easier to start again.
Any attempt to convert within Encore is unlikely to produce acceptable menus in my experience.
