We are working on a POC to upgrade our CMS from SDL Tridion 2013 SP1 HR1 to SDL Web 8.1. We have currently 600+ web applications(.Net based) 2000+ publications running on current version. We have successfully installed Web 8.1 and upgraded some sites on Web 8.1, we have tested publishing with new Httpupload microservice through reverse routing and its works perfect but i want to explore if we can use old httpupload (Tridion 2013) by upgrading\replacing jars, dlls, configs etc.
Please suggest if we can upgrade old httoupload or its fully depreciated in Web 8.1.