440
Should go in pretty easy because both are small block motors. You will need a 600 pipe and probably CDI. Motor mount should work with no mods. If the 440 was carbed then air box should be pretty close too. You may need to use the 440 carb adapters on the 600 due to the way the motor is mounted and length of adapters. All a mater of trial and error. Use parts from the 440 if you have any problems. Before you change too much, mock it all up to see if one change affects something else. When I installed my XCR in a Gen II. I found that by sliiding the motor to the left a little the air box fit with no mods.
