Unless you bring unlimited quantities of the right gear from the future with you, you are bound to be unfitter to live in the other time period than the people of that time. You will also be unfitter to live in that time period than you are fit to live in your own time period.
Your knowledge of future technoloy will be only a minimal advantage to you, because getting that technology to work will be near impossible in the past.
Ferrari ---> no gas, no road, no mechanics, no spare parts in that past.
computer ---> no electricity, no software, no one who can use it, very limited benefit if you dont programm yourself, and no spare parts once it breaks
airplane/spaceship ----> heh you dont know how to operate one be honnest, neither do oyu know how to buikld it, and even if you did you couldnt sustain it.
gun ------> you'll run out of amo, or they'll just kill you in your sleep
However, your reliance on modern conveniences, vaccines, medicine, and their absence, will make it very hard to cope in the past, while the people from the past dont have that problem.
You wont be a king if you travel to the past, you'll be a handicapped weirdo.
Better stay in your own time period, really.
And if changing history is your goal, there is absolutely no guarantee that the present you create will be any better than the one you are used to. You'll probably just prevent yourself from getting born.