I think Kevin Proctor on a 2 year deal would be a great signing. Forget the loss of strike power on the edge, lets fix our defensive issues and lack of leadership first and foremost. He is off contract and and I'm not sure if Titans will re-sign him after the amount they just invested in other forwards.
Alternatively there is Guerra (I think he will leave with Frizell going to Newy), Aubo (probably stay at the roosters), Asiata (Looking to leave for a starting spot
but probably best used as a lock), Cooper (probably retire).
Then there are some depth options that are at the end of their career like Chris Lawrence, David Gower, Elijah Taylor, Brad Takarangi. And for middles Sia Soliola, Mark Nicholls, Aiden Tolman. These kind of players would be similar to the Tagatase, Fensom, Lowe, Staggs cheap toiler varieties that are good to have as depth.