Hi there
   For what I was doing the engines were virutally identical in size...for automotive use the difference is in the height of the block and the mounting of the engine to bell housing,,,the weight difference is a little bit of everything...block...crank...flywheel etc. Same with the 8v-16v SOHC-DOHC it all adds up.
  Sorry can't give you anything specific on the trans..I didn't need to use one so I didn't do any research....but off hand I'd say the difference is minimal.
Zag