Rope or Rubber rear main seal?

76' 360 stock crank and rods, fresh from the machine shop. I removed the original rope seal when i tore this thing down, just wondering what you guys prefer, I had planned on a new rubber seal (fel pro) but i thought i should get some opinions. The crank is grooved at the sealing surface for the rope seal, are non rope seal cranks grooved also? forgive my ignorance, this is my first mopar build.