If your just looking for power then selling the 1.4 and buying a gti would be a far more financially viable option as you will get the engine/interior/features in the price. You can find gti at very reasonable prices and im sure your 1.4 can fetch a few pounds.
If your desperately looking for a project then i have no experince in engine swapping ibizas. As far as im aware the ABF (16v) is the same in both cars and the engine bay is the same size in the various models (1.4 - 2.0) so nothing is stopping you. Use the search function to explore your ideas as there are plenty of people who have asked/have experienced this topic before.
I used to own a 1.4 and the feeling of upgrading through the
ibiza ranks was brilliant, and cost effective.