Radiator Fan Switch Grommet

I ordered a new radiator fan switch and rubber seal from Victoria British for a 78 B.

After the engine warms up and creates pressure in the radiator, the rubber seal works outward creating a leak. The portion of the seal fitting into the radiator has a straight profile with no lip to hold it in place.

I have also desmogged the engine and installed a new Weber 45 MCHH carb. The only piece I can't figure out how to deal with is the EGR valve. Does anyone make a blanking plate so I can completely remove it?

Any good ideas?

Thanks,
Bill

For the switch and seal, get a largish zip tie and run through the radiator and around to hold the switch in place. Second, learn to buy Moss parts. :)
Don't no nothing about Webers though I have had cars with a couple installed.