well the 1.4 should have the exact same doors as the 1.6 and 2.0.
you can precisely fit a 6,5" but youll have like 1mm clearing.. if you do be sure to mount it with a MDF plate.
i used 5.25"s instead, and thats probably what i would recommend. the mounting hole in the door is precisely 6.5" BUT it has a flat lower part which means it's not round which means you can't mount a 6.5" without a spacer plate (like MDF) or by cutting into the placeholders of the speaker.
get 5.25"s and a Sub (less hassle).. thats good enough base for you.. basically anything is better than the original speakers. sure the 6.5" have a more distinct base. which the 5.25" hasn't but the difference is very little IMHO. and the empty space between so to say can be filled out with a good subwoofer. and heavier rear speakers. people tend to imagine that only the front speakers play a role, sure they're important, but the others speakers are as well for the complete sound experience.
kinda like modding your engine, it's no use turbo converting your engine if you still have your original header on (if you see my point) IMHO.