Since it’s an old car, stick with the stock size. Look at the sticker on driver’s door jam.
There is no " Best " tire. It depends on a lot of things. Is it only off road? Dirt? mud ? rocks? water? tire size and rim size? Hp ? vehicle weight? Is this only for a once in a while off roading and mostly pavement driving? And the big question. How much can you spend on rims and tires? Also . Do you have the motor to move the truck with big tires? Just because you have the " BEST ‘" tires does not mean you won`t get stuck