I have to disagree here. Why wouldn't you install as much as you can on the engine before it goes in? Saves time, get's things done nice and tidy. Will also save the engine compartment from getting banged up.
Your proposal might be fine for a smblk or Bblk install, but the HEMI is a very tight fit in ANY application, I usually like to install from the bottom up, but have done HEMI installs from the top, if going in from the top, no exhaust manifolds as suggested, you might even find yourself removing the valve covers depending on the style used and how much you might have to move the engine around to sit it on the mounts, you'll need to lose any booster/master, you might even have to remove the front shocks as the studs might hit the heads/covers going in...
