How much would it cost me to build a fast car?

I had a question… My mom has this really old 1995 Ford Taurus she's thinking about selling it this car is really beat up from the inside no dents from the outside though the engine is pretty bad but it still runs its been her daily driver for about 5-6years she wants to sell for 300$ but I wouldn't want her to let it go for that much and I was wondering how much it would cost me to basically make this a fast little son ***** pull the back seats out and everything
I wanted some recommendations on what engines and transmissions were good to fit this car v8 preferably with a budget of around 3-5k

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