Well i wont recomend diesel turbo engine simply because these old engine agar petrol ho tu kaam chal jata hai diesel of this size 1.0 es ke already life kum hoti hai.
Balka es sey bahtar hai get ur own diesel engine rebuilt.
Swap karna hai tu once again i will say no to toyota engines reasons i already told you plus you have g11 es main space g100 the 88 shape sey kum hota hai means i will be hard to fit that engine.
To fit it they will cut your axels, cut the gadery, even cut some portion of frame after this even an oil change will be a hard thing to do.
I know the original 1.3 engine of charade is also not designed for this car but still atleast the fittings will be siimilar.
And total expense with swap and cng will cross 50. Baki if you wanna run on CNG than go for Carbi one agar filhaal cng ka mood nahi hai than go for EFI engine it will give you consumption of over 13 KMPL or even more local bcoz of big engine small body so consumption will be better.
Prices es banda sey poch lo his shop is in mithu khan, 0300 5524958