Need more information. Are you considering reusing a geared machine,versus replacing it with a gearless? Geared machines are limited as to speed, usually around 350 to 400 fpm. Are you considering a new Gearless AC Voltage Machine? These are a good choice. they are cost efficient as far as usage of electricity, they don't leak oil, and the ride quality is usually way better. The biggest consideration is cost up front. My advice is to get an elevator consultant. they will guide you and tell you what is the best way forward. They will save you money in the long run.