The F80 from ThatsDax has already been apart if it's the balanced assembly, shouldn't need to do anything internally, just spend some quality time here on the forum using the search feature and reading the many post on proper set up for the rear wheel sprocket, the carb tuning, the mounting hardware, don't use any rubber or any other material between the engine and the bike frame......etc.
Many things here that you can uncover by spending a little time that will help you have success with your build, plus several people here that will be more than happy to give you some honest straight forward answers based on their own experiences over the last several years of building and fixing things on their own bikes to get them to be very reliable and low maintenance.
Peace, Map
Rubber side down..!