The 1.3 & 1.6 are what are known as "G-series" engines, the 2.0 is from a different series - the J series, which includes a 1.8 litre J18, the 2.0 litre J20 and a 2.3 litre J23 - the dimensions are different, so you're not going to be able to swap heads, manifolds etc.
Additionally - the J series engines have significant differences in the engine management electronics to the older G series - they use a distributorless "coil-on-plug" ignition system, making it a little more challenging to convert them to carburettor - you'd probably have to go to a third party engine management system