engine weight, 6.4 Vs a 318?

When I pick up one of the Apache heads, they feel like about 20 lbs. Very light. A little research got me some vague numbers. It sounds like 485 lbs for a stripped 5.7, no alternator or pumps other than water.
The motor could wind up with either a 5.7 block, or a 6.1 as this is a custom stroker. I just felt asking about the 6.4 would be close because of the plastic intake, etc.