If you mean lenght, that shouldn't that big of a problem with the 26. Are you welding custom mounts or are you using the GTR crossmember? I know the crossmember leaves the motor about a inch or two too high, although it does bolt up with the stock mounts. I would bolt up the crossmember, and cut the mounts down myself..The 20 and the 25 would be harder, because of the intake manifold on those motors, unless you weld your self a nice little sheet metal intake.
The stock intake mani wraps over the top of the valve cover, that pretty gay, since it makes changing plugs on an inline motor, take hours instead of minutes.
No one to my knowledge has done the AWD swap... The Jun car is RWD...