I currently have center/standard lifter seats, haven't had much luck finding offset ones. I am running hydraulic roller lifters. Yes I am using the Hughes roller rocker set and have verified the correct rockers are in the correct locations. I don't know the spring loads. Cam is a Thumper with .513int/.498exh lift. Pushrods are 5/16 diameter, I don't know the wall thickness off the top of my head.