Wednesday's first leg at Central Park ended 1-1, meaning whoever wins the return meeting at East End Park tomorrow will play in a strong Championship next season and consign the loser to League One.
With home advantage Dunfermline would appear to have the upper hand in what is effectively now a one-off cup tie. But the venues were switched because of a clash with a British and World Championship stock car event at Central Park.
Morris is thrilled to be able to play his part in the play-offs after missing out last year due to an injury, and believes Dunfermline will benefit from being at home for the decider.
"We're all very positive going into Sunday and it's got the added spice of being a derby as well," he said. "Hopefully it will benefit us that the second leg is at home. Everyone knows that Central Park is not the nicest place to play football but getting them back to East End Park, on the big pitch, probably works out better for us.
"We should have the crowd behind us. I'm sure we'll have another big crowd and hopefully we can finish off on a high and get that promotion."
Jimmy Nicholl, the Cowdenbeath manager, believes the outcome of the game will determine whether he can build or dismantle the team.
Nicholl has ambitious plans to recruit full-time players but that can only be realised if his club remain in what will be a relatively lucrative Championship. "I know there are things in place in terms of staying in the Championship and it will be great for the club, the community, the players; everybody," he said.
"And if we do it, I'm talking about building this club one day by having seven or eight full-time players rather than part-time. But if we don't do it, it goes the opposite way and I don't even get my modern apprentices, the kids. That's how bleak the situation is if we don't do it."