Best tire pressure for 69 dart with P245 60R14

Like several have posted,very much personal preference especially if its about how it looks.

If a wide tire is used on too narrow of a rim, then the tread closest to the sidewall gets lifted. That negates the major advantage of a wide tire.
245/60r14 is pushing the limit on a 7" rim for a BFG T/A Radial. In the US, Hankook doesn't offer a tire in that size.
The measurements that you need to be careful with on the front is the backspace and offset. Too much backspace and the wheel or tire can touch the upper control arm-balljoint, and/or sway bar arm. Too little and a big tire can catch the fender lip - distance is somewhat dependent on specific model.
Moving the offset further out increases the distance your wheel turns vs. the pivot line created by the ball points.

Very Generally
Pressure should be within the tire manufacture's recommended range.
Wider tire usually has wider tread and can develop more traction on smooth dry pavement if the rubber compund is sticky enough.
Narrower tire has a better time cutting through snow, water, etc and concentrating force where friction is more important than sticktion.
Shorter tire will lower your effective gearing and taller tire will increase it. In other words, a shorter tire will accelerate the car more easily, everything else equal.
Bigger tire will generally weigh more.
Shorter sidewall will be stiffer and more responsive. Taller sidewall provides more protection and maintains better contact on rough pavement.

In the US, Hankook offers a sporty all season tire in the sizes Johnny Dart mentioned, and they'd fit well on a 14 x 6, 6.5 or 7" wide rim. Obviously you may have different choices in Brazil.