I bought a 16v a year and a half ago after coming to the same conclusion that Lofty and others are pointing out. My 1.2 3-door Mk1 Clio was never going to be a 16v, no matter what I did to it.
But with all the money Ive ploughed into my 16v, I could have probably just about afforded to make a unique Maxi-replica, GT Turbo-engined car out of my 1.2. I understand the satisfaction there is in making a car like that, but it would still have major down-sides.
The bona fide 16v was developed in isolation of the Clio range by Renault Sport. I would list all the parts that are uprated, but I think its easier if you just imagine a part - and it will most probably be different.
For example: yes, you can fit better shocks, but what about the anti-roll bars, track width and ability of all the RT parts to handle the extra power/stress of a doubling in power? Not to mention the structural intergrity of the shell, cooling systems, weight distribution and handling (rather than just grip). OK, it can be done. But how about a 16v as a starting point - then going for a BB Turbo 300bhp conversion!
I know this all sounds like a big go at the idea, but its not intended that way. The worst thing to do is to go half way down the line, then realise (like I did) that a proper sorted hot hatch is a better starting point. Id just run around in your RT for another six months or so and then get a Valver just in time for the summer.