Force Applied on a Seal

I would like to ask you for information to resolve something I am working on with a sealing problem.

I have a cylinder with a vertical access port. I must install a plug to serve as a seal. This plug will be retained with a threaded cap.

I have two options: the plug wil be a cylinder, and will interface with a hortzontal sealing area. This would be a slightly raised ring that the cylinder would fit against, and the slight deforming of this ring would seal the port.

The other way would to be to use a cone shaped plug. This would mate with the port at an angle. The port would be machined with two bevels, so that the initial contact would again be like a ring, and the torquing of the cap would slightly deform this material and seal the port.

I cannot use a conventional gasket or flexible seal, due to the demands and enviroment this is operating in.

My question is, would additional torque, and thereby axial force on the plug be requiired to seal the conical plug? With the angle the plug and port intersect at, I see the forces will be applied at an angle, and I think additional force would be needed to get the same sealing.

I am basing this deformation on a situation I saw in a book where it calls this sealing "hertzian contact".

I thank you for you help.