1987 Grand Marquis LS HELP

Whats up everybody, I'm not a big car guy and I'm looking to do some work on my 1987 Mercury engine. It has a 5.0 liter 302 I believe it is. I'm grabbing a magnaflow dual exhaust for it, I got that far. And then from there is where im going to need the help. I don't want it to be drag car fast just to bump it up to about 250 or 300 horses so it can have some more umph behind it. So I wanted to know what are the parts I would need to get the performance up there even if it's not near the horsepower goal.

Thanks all.