I've never seen more than two motor mounts on a rear wheel drive car. The transmission also has a mount near the output shaft that should be replaced when changing the motor mounts.
Just buy the new stock height solid ones from SCP or the slightly taller solid mounts from Rich at MN12 Peformance. I believe both places also sell solid rubber transmission mounts. I've never heard of that place you listed before. Beware all mounts are not created equal, some of the solid ones are hollow and tear easily.
David