Assuming it's the petrol one they either came with a L18 or L16, my little brother has just inherited a 1984 Kingcab that my parents have had since new. Were the most powerful ute on the market at the time with 105bhp and a five speed gearbox, both quite revolutionary for a ute at the time. My brothers kingcab beat my 1200 sedan in a race up a big hill near Nelson, NZ. The wonders of being able to race under 100km/h!
And that's in a relatively heavy body c.1300kg, must have quite a bit tof torque?
As to what parts you can use, the Stanza used the L series engine and apparently alot of those parts can be used in a 1200 with little or no modification? Twin carbs are very easy to get for the L series as both the 180BSSS and 1600 SSS used them on this block.