The 21-year-old defender, equally adept at right-back or centre-half, was a first-team regular for Eastbourne Borough in the Conference South last season following his release from Fratton Park and a spell with the Nike Academy.
Tallack made eight appearances while on loan at Tatnam from Pompey in 2012 and donned the red and white jersey once during Poole’s Southern South & West title-winning campaign having signed as a free agent.
Killick told the Daily Echo: “Lewis is starting college in Bournemouth in September so it might be quite convenient for him. He’s going to play in a couple of games for us first and we’ll see how he gets on.
“He’s a very good player and we know all about his attributes, it’s just whether we can work something out.”