Funky and Slinky are getting along fine
A decent set of 18" will go well on a R34, fill out the guards so it sits flush with the guards.
Get a decent set of coil overs and lower it and your all set.
+ it will improve the handling of your car.
Depends on which spoiler you got, R34 4 doors looks better without it unless you got the boot lip spoiler, which adds a nice lip to the end.