Convert Rage MP Server to FiveM and implement full backend for it

I already have a full Grand RP project running on Rage MP with the entire front-end finished. What I now need is a seamless migration to FiveM and the completion of the remaining back-end code (about 90 % still pending)... (Budget: $250 - $750 USD, Jobs: API Development, API Integration, Backend Development, Database Management, Game Development, Game Testing, JavaScript, Linux, MySQL, PHP)