Leak-proof plumbing of an old-fashioned wall-hung toilet?

What is the best way to ensure that a wall-hung toilet is leak-free at both ends of the flush ell? I am using modern fittings inside the tank, and the plastic fitting at the bottom of the tank does not take the torque a brass fitting would. In addition, the rubber rings provided with the ell seem not to be compressed properly at the spud either. I have used tape dope and "Tighter-Than-Tight" dope, which help, but I would be grateful to know the best approach to this problem.

Public Comments

1. I am restoring a old wall hung. Oak surround and copper tank with the old pull chain flush. I have not got as far, with leakage problems, but forget the pipe dope. Clean and throughly dry connections, get a clear silicon based sealant, apply a good bead to the base of threads, loosely tighten jamb nut (note you do not want the silicon to stick to the jamb nut, lube with pet. jel.), and let it cure 2 days minimum. You just built your own silicon gasket, trim off excess give jamb nut a 1/4 turn. and test. Those old pots are obsolete for gaskets we learn to build our own.
2. youre a homeowner? why haven't you used duct tape of silicone caulking