New torque/ did we screw up ? 360 magnum

No the flex plate was for the 5.9 magnum ' s balance...ok then what will happen since my friend put the trans on tonight, we are screwed and need to put back that weight that he removed ? Just really wondering what can be the worst case scenario if we start this ?
V-v-v-vibr-r-ration-n-nss... eat bearings... break things...