Install the rear main and timing cover seals reversed. Use RightStuff sparingly on the sealing surfaces of the rear main seal cap. Fill the voids of the stock style seal cap with RightStuff. As stated seal the upper ends of the head gaskets with RightStuff. Seal the crank key. If the block has side bolted mains chamfer the holes and use an o-ring under the washer. Make sure the 0-ring fit for the distributor is tight. Pressure test with no more than 5psi and soapy water in a spray bottle. There are 2 nitrous motors out that we had to put vacuum regulators on that were sealed like this.