The perches on the new subframes are about 2" tall... and the perches on the oldstyle subframe are 3 - 3 1/4" tall. The rubber insulators are correspondingly longer/shorter to compensate.
Also I don't believe the mounts were changed for the JZA70... I think they were changed to reduce engine vibration into the subframe to smooth out the car even more. The new rubber design is definitely much more absorbant than the old one. (weaker too) Toyota wouldn't go to a weaker mount for a significantly higher HP motor. There must have been another reason (vibration dampening)