Very few L-engine parts can be used on a 1200 without modification. The carb is larger, different bolting holes, the manifolds are different, etc. The engine does not "bolt in", but is small enough to fit with some modification. The transmissions are very different.

The one thing that might fit without modification is the alternator. The 620 alternator (50 amp vs. the stock 1200 35 amp) bolts right in. The 720 alternator might also.

my mate has got two 720 utes so i can have anything off them :) might have a look at them then

did they twin SUs on the 720? or were they hitachi

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.

what engine does the 720 ute have?? what compents can i use for my ute out of a 720?