Understandable. I know where you're coming from, and I know what it's like to want to compete in a car you like, rather than just picking the obvious one. It's nice to see more shapes on the stages, rather than endless Escorts, Corsas and Micras, so I can't criticise you for wanting to try. Weirdly though, with the Clio, it is probably the best budget 2.0-litre car out there, so it's definitely worth considering.
@Nathan Evans goes well in his, even with a fairly modest spec relative to the top cars in the class. Something to think about anyway.
If you're keen to stick to the 1400 though, I'm sure it's possible to get decent power from it, it might just cost you a bit more money. Is the 1.4 related to the 1.6 engine? If so, you might be able to rob some bits from one of those, in terms of exhausts/inlets, maybe even cams. Alternatively, you might be able to have some cams reground by one of the big cam companies (I think Piper do it), so that would be worth investigating. Get someone to look at the head to see if it can be improved, maybe see if you can get away with skimming it a touch to give you a bit more compression. I'm sure you could make throttle bodies work, you might just need a custom inlet manifold. Beyond that, it's going to be pistons and rods for high compression and all the big bills that come with it ?
Best thing will just be to get as much weight out of the car as possible. It always staggers me how many cars I see in service parks that are carrying needless weight. My Escort was terrible when I bought it; so many badly thought out changes that were adding pointless weight. A bit of thought when making brackets or mounting things can soon add up. The guy who built my car had gone to the expense of fitting expensive Group A top mounts, plastic windows, doing a wide track suspension conversion, but had then left most of the bitumen sound deadening in it
At least you can still take advantage of all of the nice suspension/braking parts out there for the Clio too, regardless of which engine you use.
My only other advice would be to try and learn to speak some Eastern European languages ? They do seem to be much more willing than us to try different things, that's for sure.