Should I Replace Gas Tank - Car Sitting for 3+ Years

I purchased a '90 hatch 3 years ago and the car had been sitting in his driveway with no motor for about a year. I'm getting ready to put an old 302 into the car while I build the 351W. Is there anything I need to do to prepare the gas tank (additive, remove it, empty it???), I have no clue how much gas is in there, or should I just install a new one?? What about the fuel pump??? Thanks..
 
I'd want to inspect the inside of it and pressure test it if possible.

In the old days with bikes that had rusty tanks, I'd Kreem them. But I think it's more cost effective to replace a fox tank with a new unit (they're 100 bucks or so as I recall).

Good luck.