I take it the car was bought a while back and some of that cost is maintenance but I can see why you want to finish it off rather than buy something already done.
So onto your question; when you say safely, there is safely to give it a squirt on the road on the weekend every now and then and there is safely where you are going to take it to the drags and circuit all the time and flog it mercilessly every chance you get.
The first one can be done on a stock motor in good condition with the right bolt ons and some valve springs.
The second one will need a built motor for any hint of reliability.
Obviously the bolt ons will be similar eg; injectors, fuel pump/s, surge tank (you can get away with not having one for street use), exhaust, turbo mods, intercooler etc etc. All of this info regarding bolt ons can be found pretty easily with the search bar. Take a look through the 400rwkw section or even the 500rwkw section and see what people are using.
Hey did you know your cradle is orange?