The new Penrith playmaker made his Bravehearts debut at Workington on Tuesday night and ended it on the winning side as Steve McCormack's men beat Tonga 26-24 in a thriller.
It was an intense baptism for Wallace - no stranger to the big occasion as a four-time New South Wales player - and he was left wanting more.
Qualified for Scotland through his grandmother, he wore the team outfit of a kilt and heartily sang Flower of Scotland both before and after the match.
"I couldn't be happier with the night - it was even better than I expected," the 28-year-old said.
"It was a great atmosphere during the game and the atmosphere in the changing room afterwards couldn't have been better.
"It was all a new experience - I've worn a kilt a couple of times before but that was the first time I've sung the anthem properly. I can't wait until next time now."
That will come against Italy on Sunday in a match that, if Scotland win, would put them on the brink of qualifying for the last eight.
Tipped to achieve little by many, McCormack's men have given themselves a more than fighting chance of making a real impact.
"I think we'll be all right," said Wallace.
"It was my first hit out in about eight weeks so I'll probably be better for the run. I feel a bit sore but that's expected - they were one of the biggest teams I've ever played against. We'll have a light week and be ready for Italy."
Wallace, who has been nicknamed 'William' by his team-mates in homage to the great Scottish leader, required all of his experience against Tonga on a night which was not settled until the last second.
Scotland led 20-4 at half-time but trailed 24-20 with eight minutes left. Matty Russell's try and Danny Brough's goal got them in front again, but they still had to survive a last-gasp video decision to get the win.
"I thought we were gone there a few times," said Wallace.
"We had a couple of lucky decisions go our way, which kept us in the game, and Matty Russell came up with the last try to win the game for us.
"In the first half we did everything we spoke about and did everything right. Second half they came out with more fire and got on top of us.
"It was a fantastic defensive effort to have that much possession against us. We did a great job. We were starved of possession but then got a couple of attacking sets and attacked their line and Matty got over."
- Sports & Recreation
- Flower of Scotland