To go from Tag Sprint to Road race isnt much to do. Gearing change like Ray said for most Tag engines and tracks this will be a 16T driver and sometimes a 15T. Lay back your seat so your not sitting so upright. Front brakes are always good to have.
What Tag engine you run? If you run a Leopard you may want to get a road race clutch.
What series do you plan to run with?
Before you go and make changes to the kart, you might want to check on the rules in the area you plan to race at. Not all orgs allow the seat to be laid back. If you plan to run a KART/MARRS event, I can help you here. This series races in Ks., Ok., Ne. Around here we all run a 16 tooth front gear. We have ran both the sprint & R.R. hub and biggest difference we seen was that the R.R. hub lasted longer.