Well, I made a start on moving the petrol tap to the rear of the tank from the centre. What I thought was a steel reinforcing plate at the rear (fig 1), and into which the tap would be installed, turned out to be a copper blanking plate. After drilling two holes in the copper plate, a difficult look inside revealed weld-nuts on a separate plate.
Off came the copper blanking plate, which was sealed to the tank with lead, to reveal all. Bugger! The two weld-nuts were rusted to hell and were intended for a tap with wider bolt spacing. No way I can utilise these weld-nuts. Drilling out two spot welds, released the weld-nuts plate, leaving a mass of holes (fig 2).
Fig 1 Before the truth is revealed Fig 2 After the debacle
Solution? Fabricate a new steel plate with two rivet-nuts (centres 35 mm apart) to fit inside the tank, then install a 2 mm steel plate on the outside of the tank to create a clean surface for the petrol tap. The next problem is bonding the outside plate to the tank because the mating surfaces are not perfectly flat and the bonding product must be petrol resistant.
Leading is the obvious solution, but I don’t have the skill or facilities for that. After much internet search and a telephone conversation with a very helpful guy at Loctite I deduced this. Some anaerobic gaskets are petrol resistant, but need a very flat surface. Silicon gaskets are not petrol resistant. Some epoxy bonding products are petrol resistant, but can be brittle. My conclusion is to experiment with some Chemical Metal, manufactured by Plastic Padding. If a test piece works out ok, then Chemical Metal it is unless someone can recommend a more suitable product.
