I have a 305 V-6 on a 1,200lbs engine stand I still have to put a 4x4 under the front, because it sags down a bit, I have aircraft quality bolts grade 8 holding the bellhousing on the block and grade 8 bolts to the engine stand I don't want to find the engine on the floor one day.
If you look at my link you can see the 4x4 under the front of the engine. I was foing to build a 4x4 frame to set the motor on but it looked way to pretty up in the air.
http://community.webshots.com/user/modelman102 Jake