"I've seen Morison a few times when I've covered the Wales games.
"He's a bit like me, a big target man who makes his presence felt," Roberts told the Pink Un.
"He had a good season at Millwall and scored plenty of goals. He came into the game late and played non-League for a while but I think he will be raring to go.
"Holty is probably the first name on the manager's teamsheet most games, I would have thought, with the two seasons he's had. But you need a strong squad.
"I saw Vaughan a couple of times last year at Crystal Palace. He's not really achieved what he should have done, through injuries.
He's been very unlucky with injuries, but he's still very young, at a good age, only 22, and he has come from a Premier League club and he's got a lot to prove, not just to himself but to other people, to show what a good player he is.
"Simeon Jackson found it hard to settle in to start off with but once he started scoring goals towards the end of the season he looked a different player."