I was told to retightnen the head, any tips? Should I check tappet clearance at the same time?
Yes you should re-check the tappet clearances and set to 0.008" inlet and 0.006" exhaust (T140 with standard cams).
Re-torque the bolts in the correct order to 18 ft/lb for the 3/8" bolts, and 16 ft/lb for 5/16" bolts.