As per my build plan, I knew that I could not install the oil tank (and therefore the oil plumbing) until the primaries were installed. The four primaries were unpacked and the mounting ends were compared one by one with the available mounting points on the engine block. In this way I was able to identify which primary went where (they align uniquely with the mounting holes in a sort of jigsaw pattern).
Each primary then had labels removed and cleaned, and then laid out in order ready for installation. I knew the advice was to start with Primary #4 - the one closest to the rear of the car.
The bolts holding the gasket in place were removed and set aside, as was the gasket itself. The mating surface was then cleaned to remove the residue glue left behind by the masking tape that was covering the exhaust ports. The gasket was then replaced and held in position by a couple of the bolts positioned at the middle and right hand end.
Taking primary #4 I was then able to lift it up and over the skin, and then feed it carefully through the side skin, lowering the mounting plate into position over the gasket. Bolts were installed finger tight and the process repeated for the remaining primaries.