I picked up some silicone sealant that is meant for use with gasoline and coated all the surfaces, a little extra at the flattened out ridge areas. Then with a couple of small strips of masking tape to hold the bolting flange in place inside the tank I carefully worked the pump assembly into position and started in a long screw supplied in the kit into the bolting flange on opposite sides, then pulled out the masking tape. Next started all the rest of the screws and then started tightening them all. I have to say this was a good sized mess. Trying to get all the screws started through the cork gasket, through the tank, then into the mounting plate. A lot of planning ahead made this not a disaster.
I tightened all the screws until a could see a consistant bead of silicone being pushed out from under the gasket.
Then cleaned everything up with lacquer thinner, including the tank, and gave it a couple coats of spray can undercoater.
This process took me almost 8 hours to complete, and does not even count taking out or putting it back in the car! More work than I would have thought.