It has come to my attention that there appears to be a dimensional error on page 5 of the Powerhouse plans. On "Frame Side View" (upper left), the dimension of .281 for the distance from the edge of the frame to the location of the push rod bracket holes, should be ~ .210 to .213 instead. If .281 is used, then the leftmost pushrod bracket located 2.156" away will be too close to the cam gear.
Many thanks to Jay Bolyard and his son Erik who caught this.
I'm very surprised that this has not been brought to my (or Dad's) attention until now as the plans have been around since 2001!