it doesnt not shake at idle and the the tacho reads 700rpm. The shakes happen when you start to release the clutch( pedal just an inch off the floor). when the clutch is fully engaged, vibration will disappear....Im starting to think its a clutch problem.
spikot bearing may be worn or if the motor has been out it may have been missed. this will cause bad vibration. i just pulled a motor down that had not long been rebuilt buy a mechanic and there was never a rear main seal installed.