The two-time champion, which is keen to become a genuine force in the A-League after a period of under-achievement, already has acquired front men Shane Smeltz, Alex Brosque and Bernie Ibini.
But Arnold, who joined the club in the off-season after a brief stint in Japan with Vegalta Sendai, wants an international-class marquee to put the icing on the cake.
"We are still negotiating with Ameobi, but he is one of six international strikers we are talking to," Arnold said.
"The other five are Europeans, two of whom have played in the World Cup in Brazil.
"They all have different agents but I have spoken to most of the players personally.
"They've had and are still having good careers and still have an upside to their game and are not finished.
"It's a long off-season so I am taking my time with this.
"I have no deadline and certainly no pressure from anybody at the club to sign players.
"I am being patient because I want to make sure that we get it right.
"I need the right player and one who will come to Sydney FC for the right reason and that is to play good football and be successful.
"Some of the players we're talking to are out-and-out No 9s who are lethal in the penalty box while others can play in other areas, including the No 10 role.
"Brosque can play anywhere across the front third but we need somebody else who can complement Smeltz, Ibini and Corey Gameiro up front.
"I want depth and competition for places."
Sydney has 19 players on its roster.
Two more places will go to under-20 players, leaving Arnold with a spot for an international marquee and one for another player.
Arnold said he hopes to have a wealth of striking power at the club by the time the competition kicks off on 10 October.
But he admitted he still has not settled on a preferred formation to suit his squad.
"We are practising a system to take to New Zealand for the exhibition matches and then we'll decide whether we should use either Plan A or Plan B,â€ he said.
"When the real pre-season starts eight weeks before the start of the competition we'll settle on a system.
"It could be anything from 4-2-3-1, 4-4-2 or 3-4-3 because we have got to be adaptable."
Arnold said he was interested to note that most teams at the World Cup in Brazil have adopted a three-at-the-back pattern.
"Netherlands, Costa Rica and Mexico have gone away from the back-four," he said.
But what impressed Arnold most is Germany's physical qualities.
"The way they play, the Germans have shown that the modern game is not only about technical ability but physical capacity and mobility all over the park," he explained.
"Germany's rout of Brazil was an outstanding attacking performance.
"Most teams have concentrated more on attack and neglected defence."
Arnold said the mobility of players on the pitch and their rotations were something he would work on with his side.
"The rotations, the timing of runs and the attacking combinations were some of the highlights of this World Cup," he said.
"You can only take bits and pieces from a World Cup to use here but I'm keen to build a modern system to suit the players I've got.
"I want an attacking team because this World Cup has shown us what rewards lie in store for those teams that are prepared to take risks.
"If you look at the really good teams, a lot of them have star quality in the front third and the strikers work very hard.
"That's what I'm trying to build at Sydney FC, with six or seven quality strikers vying for three or four positions."
Arnold said he was confident that his forwards will get the required service in order to unleash their striking power.
"I'm very happy with the men I've got at the back and in midfield," he said.
"Playmaker Milos Dimitrijevic is an excellent player.
"So are Sasa Ognenovski, Nikola Petkovic, Pedj Bojic, Matt Jurman, Ali Abbas, Terry Antonis and Nicky Carle.
"We have quality, no worries about that, but it's not about individual skill and I'm confident that they will jell into a team.
"If we are consistent and we work hard in defence the rest will follow."