yeah, nissan design is, instead of adjustable valvetrain, they "adjust" the clearance by using many different sized shims available for the lifters... far as I know it's not many different sized lifters, I think the lifters are just a fixed size but then each lifter takes a certain shim between it & the cam... it is a tedious process because you have to install the cam & torque it down, then measure with a feeler gauge at each lifter to determine the correct shim, then take it all apart, install according to what you measured, then reassemble torque & check again... it isn't as easy as an adjustable valvetrain but it isn't as hard as trying to fly to the moon so it's all relative really... I would think that any machine shop well versed in this procedure shouldn't have much issue with it... best way to do this I'd say is to remove the heads & send the heads out to a good machine shop, have them freshen the heads & install the cams for you, then just reinstall the heads when you get them back...
edit, I guess on the VK it may be possible that instead of varying shims they vary the lifters themselves, but even if that was the case then the procedure would be the same... honestly I doubt it though, I think they still use shims..
must be nice
