I´m only asking why you want higher gears? on recent post you asked about better performance and now with this "mod" you are about to kill it and get even worse than stock...
if you want lower rpm on highway, you can swap 5th gear wheels for some diesel one, or from some other engine which is connected to this type of gearbox...
But
to swap gearbox wou will need:
- at least change the way of clutch release -16v is push, wheras VT is pull type (in worst case, complete set -flywheel, pressure plate, friction plate)
- i´m not sure if the shafts and hubs are same, so you will need also these..
..however if you have a complete donnor car its easy (1 day job) and I don´t know why you asking