i have a charade 84/85 as well. I wanted to change its diesel engine last month asked the same question on this website. Xulfiqar also advised me to go with a charade engine. taking his advice, i have put in a charade petrol 1.0 litre, non turbo engine earlier this month. This engine gives good acceleration and the fuel consumption seems reasonable as well.
Although i was also very tempted to put in a bigger engine but I'm now glad i took Xulfiqar's advice because the new engine is powerful enough. Although it's 4 speed, compared to my 5 speed diesel, it is sufficient for the car and i didn't had to change the axles etc.
Alterations sometimes work and sometimes they don't. If you want a relaible car, keeping it simple would be a good idea.