I have the 6901 in the 318 I stuffed in my Duster this spring. Great bottom end for what it is, I think some tuning problems are hurting me at the higher RPMs though. It hits a wall just before 5000.
I had the same experience with a 318. I believe its the heads holding it back 318s though the lift of the stock cam is just under .400 so it is a bit of an upgrade.