You should be able to get the engine into your '72 with most, but not all,
  of the tin on. The rearmost pieces must be off and the plastic portion of
  the oil fill tube must also be removed. 

  The confusion you are having with Haynes may be a mix-up between instructions
  for removing engine alone vs. engine with transmission. 

  When I put the engine into my '74 in May, I installed it in the car with 
  the front and side tin on but without the fan housing, fan and exhaust
  system since I had no helper and wanted to keep the weight and akwardness
  down. Without the fan housing the type IV is barely larger than the type I!
  The engine install was a piece of cake. It probably takes a little longer
  this way since attaching the heat exchangers and fan housing is a bit less
  convenient when the engine is in the car.

  Regarding the seal, I took the old one out before I pulled the engine and
  put a new one in after installing the rebuilt. I'd suggest putting the
  seal in before installing the carbs and air cleaner on a '72 since there
  is no hatch to gain good access to the front of the engine.

  Congratulations on being nearly done!

  Dave