the 2.0 16v will not fit your gearbox because its a big block engine, where as your 1.4 is small block. You will have to use the gearbox from the 2.0 16v. Have a search on here theres been loads of questions like this before.
Many years ago I did all these convertions, I have done a 1.2 to 1.4 (nova) then 1.0 to 1.6 to 2.0 16V. But I can't quite remember all the compatibilty options. I think my birds Mk4 Astra has an f13 Gbox and if I fit an F16 or F18 then as far as I remeber the drive shaft inner CV's dont fit, so I would then think to myself OK I'll use 1.8/2.0 drive shafts for a Mk4 Astra but then I'm thinking will these drive shafts fit the outer CV's!!!!!
Can someone please refresh my memory from my Nova days.