Do not ever overtorque the rocker shafts , I saw an engine 2 years ago at one of the machinists I use , they were being asked to warranty the engine & wanted my opinion on it , the shaft was crushed oval , he 2 rockers on each side were discolored from heat & had welded to the shaft , the piston had exploded from hitting against the stuck open valve , the only savable part was the heads , possibly just one head !
the machine shop had not installed the rockers so no warranty