I called Edelbrock about the AMC 4.0 head, and it weighs 41lbs, which is a savings of 25 lbs over the stock 66lb head.
The reason that it isn't lighter is because it has a 5/8" deck cast in. So far Summit has the best price, just under $1500.
It should be popular with the Jeep/offroad crowd. 8)
---Craig