hmm
well i stuck the punto 75 engine in mine, take the cam cover off and look to see if it has a cam stamped 866. if so the cam will be better than the 4x4 cam. the later p60 engines came with it, and all p75 engines had it standard.
i stuck with the ecu.. the only thing you will have to do is install an in line high pressure fuel pump.
with the ecu you will have the built in immobiliser to contend with. its pretty easy though, i gave a diagram out on fallouts project thread. you just tape the cars original key to the receiver then hide it somewhere say under the sound proofing heh.
really theres only like 5 wires that have to be connected, theres loads on the punto engine loom that can be take out, like all of the alternator and starter wires, the oil pressure light (which i remember is a yellow wire on the punto loom) and the dash temp gauge wire. the original panda loom has all of these wires in the right place so just reuse them. the ignition wire (for the coil pack or the white wire that plugs into the carb) can be used as the ECU's ignition live input (orange wire)
you can add the "injector" light (which is the engine management light) and the CODE (immobiliser) light if you want to, you have to wire the injector light through a bulb then earth it, but the CODE light needs to be wired through a bulb then connected to a constant or ignition live. (if you hook it up to a constant live, it makes the bulb flash once every second or so making an awesome theft deterrent light.... mine is connected to a 3 watt LED luxeon star that makes the whole cars interior flash at night. as soon as the immobiliser is lifted when you turn the key though the light stays out while the engine is running)
also while the engine is out, i would change the hard to reach crank/cam oil seals i did all of mine on fallout and the engine has not lost a drop of oil since which in itself is an incredible thing.
could also consider an alternator upgrade too be on the look out for the 95 amp alternator some 1.2 puntos had, it will bolt right on with no mods needed if you use the punto engine.
oh and note that the 999cc and 1.2l fire engines do have differant block lengths. meaning that the 1.2 engine sits 2cm taller than the 999cc.. just enough to stop the original 999cc exhaust from reaching the manifold. you can make a spacer or do what i did and cut some pipe out of the donor car's down pipe (the part that holds the lambda/oxygen sensor) and weld it to the original 999cc down pipe to make it 2cm taller.
given you dont have the cat built into the manifold (which i think only mk2 puntos have) the manifold the 1.2 engine has should work fine with the panda's down pipe so long as its a twin outlet. (hmm i think only the punto 75's had the twin down pipe.. i think the punto 60's had the single down pipe... let me know..)
hmm what else.. ahh just use some pond pipe hose connectors to connect the puntos heater matrix coolant pipes up to the pandas. mines worked fine that way since i installed the engine. doing it that way means you get to keep the heater pipes to the throttle body.
its up to you with the flywheel..
you can bypass the fueling system say if you wanted to use a carb setup by just having the injectors unplugged and use the ECU to only drive the ignition (man i love these ECU's) it may throw an EML but it will be because the exhaust sensor would be detecting strange burns from the engine using a carb.. you may actually be good with it though. theres no limp mode on this ECU so the worst you will get is the light lit up and if you choose not to wire that in you'd never know.
just note that the 1.2L engine does not have anywhere to install a cam driven fuel pump, so just use a solenoid pump. (i use 2 if one breaks down, the other keeps going. i just check them to see if both still work)
