we do sealing like that in this video
use anti silicon degreaser, aply the sealer with a 0.080 rope and put together. Dont touch! It seals like an O-ring. I use this trick with the gasket on my 727, i put it together and tighten the screw just a small amount, let it dry over night and then tighten. The sealer fix the "uneven" steel oil pan.