The standard diff ratio in a Ute is 4,11 to 1 & was intended to help the short stroke, low torque 1200 engine to haul the full rated load that a ute is designed for.

The A14 engine has a 7mm [1/4" longer stroke as well as a larger bore & it develops a very useful increase in torque.

If the Ute is to be used as a toy rather than as a workhorse then a switch to the 3.9 to 1 ratio found under most L series powered models [with live rear axles] will cut the revs without hurting performance noticeably.

Using a tyre with an outside diameter of at least 575mm is also a good idea. I recomend 205x60x13's on the rear as these will help fill the wheel well without rubbing & are readily available at modest cost.
A 6" wide rim is perfect for this size tyre.

The five speed sounds good but is both difficult to obtain & expensive when found, but in addition to the above alterations, it would be recomended because at highway speed in 5th the little sucker will be singing sweetly.

For international members the legal highway speed in most areas over here is 70mph [110kph] not 55 mph [88kph]& I have never been 'pinged' at 5kph over [73mph] which is a fair clip for a little Datsun to sustain.