The Irishman was on target again with a double on Friday night as the Light
Blues claimed a 3-0 win over Airdrieonians to book their place in the fourth round of the Scottish Cup.
Asked about the summer arrival's impressive goal haul, McCoist said: "It's probably what I dreamed of to be honest.
"I knew the big fella would come in and score goals. It's exactly what we would have hoped for and I still think there's more to come from him.
"He's a very important player for us both on and off the park.
"At this moment in time he is our top goal-scorer but he is also a great man to have around the club which, for us, is just as important.
"He's a good one for our younger players to look up to. We are lucky in the respect that we've got good pros at the moment and that's vital for us."
Rangers will find out their opponents for the next round when the draw takes place on Tuesday.
Top-flight clubs enter the competition at the fourth round and McCoist is optimistic about Rangers' chances of competing with Scottish Premiership opposition this season.
He added: "It would be another test. If we get a Premiership side we will just have to deal with it when it comes.
"We've got a group of players who have had top SPL experience so I would be very hopeful we could give a good account of ourselves against a top team.
"I would take a home tie, which would be great. I think that's all you can ask for.
"I wouldn't start singling out teams who we would want or want to avoid. I don't think we are in a position to do that but if somebody could offer me a home draw I would take that."
New Airdrieonians boss Gary Bollan said: "I take a lot of positives out of the game, the way they worked hard for each other.
"We came here with a game-plan and we kept our shape very well. The plusses are that the young lads who came into the team did very well and I'm delighted with them."