checking valvetrain geometry with a dial indicator

The measurement he is referring to is lifter preload. It can be measured in conjuction with an adjustable length pushrod, or with one of your existing ones. I know that either Comp Cams or Crane Cams website has step by step instructions (with illustrations) to show you how to do this so you can figure out what length pushrods you will need. I doubt you did any damage to anything inside your engine. A magnetic base for your dial indicator is needed to make these measurements - hope this helps!