You would have to consider how much modification is required to make the engine and box fit, and are these mods revereseable.

in how good a condition is the pinto engine/box?? How long do you expect to get from it??

If you have to make major permanent mods to make this engine fit, and its in an 'unknown' condition (ie second hand with no documented history) is it worth the pain makeing the mods only to find in a short time, the motor/box dies, and you need to rebuild something anyway.

Sticking with the datto stuff means that changing bits around is a little eaiser, and requires less specific knowledge.

If datto parts are harder to come by than pinto stuff then perhaps the pinto is the way to go, but its really a judgement thing.

I dont have any real bias towards any particular motor, but i would try to stick with the datto stuff, just for simplicity.

Whitesedan its not worth to make just guesses. A wedge head has nothing in common with a hemi. You look like an idito to try and clarify yourself even on a sunny day.
The WRC winning escorts always ran with the kent based cosworth engines not all cast iron pinto. I inherited 5 escorts from my uncle who went blind (macular) and who was also blind in love with them even though they where rusty, unreliable, always breaking diffs, boxes, blocks, overheating cast iron heads you name it. Others had the same deal and preferred the lighter more compact kent series. Its a behemoth of iron. Also to make NA 160hp on a pinto is very expensive compared to an L series which will make 30hp more over a pinto and always have in all out rallye setups. The escorts advantage was its almost 1200 datsun-like weight and quick responsive rack and pinion. Apart from that the Fj20 weighed a little less and made more from stock so I put one into an escort and finally enjoyed one of the stupid things. Tyrie Eskys without the boat anchors are featherweights and still lightweight with them, even one of my stock high comp pinto escorts beat factory alfa romeo gtv6 on acceleration but not on top end, The alfas where 300kg heavier. Therefore you cant compare a heavy 720 to a lightweight escort. Also your 120y`s 4agze is well tuned? Does your 120y weigh much more than the eskys? It probably does as the 4agze is quite a heavy engine with all its ancilleries like I said on another post 130kg for a normal 4age vs 118kg for a Ca18de and add another 25-30kg for the supercharger and ancillaries. Most 120y I went up against with their worked L series left me and other Eskys for dust. Even heavier Datsun 1600 and stanzas did the same. Trust me if the L series is in a escort it will outdo an equally tuned pinto not just because of the weight saving. Boat anchors are jealous of the things. Hey there in the U.S. good luck there with the free gift, I bet it will be more pain than gain if the pinto you are getting has a cast iron head and is the same size as the pinto here. I predict an unfinished project or a project that will ruin a good car and will be scrapped due to lack of appreciation. Unless of course you pour big bucks into alloy Esslinger heads or work the internals and boost the hell out of it. Either way what seems cheap at first will drain your wallet faster than any other setup. Good luck to you and most of all good luck to the poor little datsun that receives such a lump or iron.