RTV works for me. If you have a 2 piece mount and you install them with the outside ends hanging down then when the engine is installed in the chassis it will tend to rotate the outside ends up. Depending on the clearance between the bolts and the holes it could be quite a bit. Preloading the ears in the direction the engine weight will force them later will reduce the movement.

I prefer to use studs that are threaded on both ends with a smooth shank section in the area that the engine bears on. It makes installation and alignment easier plus the smooth shank has more bearing area.