There is a conversion kit available to fit the the Lancia twin cam from the Delta HF into a Uno. However, it's expensive and you will still need a lot of extra parts and work.
As Unclechuchu says, the Uno was never fitted with the twin cam as standard therefore there are no easily available parts from other Fiats that you can use. You either buy a conversion kit or you fabricate your own mountings. Don't forget as well the Uno gearbox will NOT bolt up to the twin cam without an adaptor at least, so you'll be looking at fitting the twin cam gearbox and driveshafts as well. Which will mean even more work and modification...!
The easiest swap for your car is a bigger FIRE engine. Anything from the 1108 to the 1.4 SuperFIRE will swap with your existing engine and also will hook up to your existing gearbox and driveshafts. To convert from a FIRE to the Lampredi ohc (1116cc/ 1299cc/ 1301cc/ 1372cc/ 1.5/ 1.6) will require engine mounts and gearbox from a Uno already fitted with one of these engine, along with some wiring changes as the ancilleries are in different places. You can however get all these from a Lampredi equipped Uno if you can find one being broken for spares.
Lastly, whether it's a Uno mk1 or Uno mk2 the principles are similar as they share the same floor pan and chassis. There are some minor running gear changes to the later model such as the addition of fuel injection for lower spec models and different gearboxes used, but the parts are nearly all interchangeable between the models.
There have also been a number of threads covering engine swaps already, I'll have a look and see if I can find them for you.
By the way, welcome to the Forum!
