If I were you, and try not to take this the wrong way
I would try to buy a car first, familiarise yourself with it and driving and owning a car
fix up what’s wrong in it
get someone to at least look at the brakes
renew the cooling system
do a stage 0 on the engine and rest of mechanicals (getting the car back to how it drove when it was new, standard specs)
then after a year or two, think about doing the mods
it’s a slow process but that’s how to do it right