While Harris made 20 in that match, she has at times provided valuable top-order firepower for the Heat alongside Beth Mooney, including setting a WBBL record with a 42-ball century in Brisbane's win over Melbourne Stars in December. There were some fears she had picked up a niggle in last weekend's semi-final against Sydney Thunder, but Heat captain Kirby Short was confident the allrounder would be fit to play in the final.
"She's actually the fittest she's ever been, so part of the reason she's launched onto the scene this year with both bat and ball is that she's in the best physical condition that she's been in," Short said. "And that makes a big difference in the capacity she's been able to perform in both facets of the game so she's actually been travelling well, which is why we feel pretty good about tomorrow."
While Harris' strike-rate of 150.40 is one of the best in the WBBL, she has also taken 13 wickets at an average of 19.07 and a team best economy rate of 5.90.
"Grace is a once-in-a-generation type of player for a lot of reasons," Short said. "We talk about her being our team 'crazy' in the most loving way possible, in the sense that she can do things with bat and ball that essentially no woman can do in the world in cricket and part of that is her mind set.
"And she plays with such freedom and that carefree attitude, and the hundred she scored at the Gabba was - her sister actually raised in a meeting that we had the other day - just talking about how much she was genuinely just loving doing it. And I think if you just let the shackles off and just set her free what happens, happens."
One of Harris' challenges could be to contain the WBBL's leading run-scorer, Ellyse Perry, the Sixers captain who has amassed 744 runs at an astonishing average of 93.00.
After the Sixers' claimed a thrilling Super Over win over Melbourne Renegades in their semi-final, Perry said it was important for the players to put aside any lingering emotion from the victory.
"We've been very conscious of making sure that we moved on from last weekend at least for the time being and we had a really good chat about that on Tuesday," she said. "I think it's really important to acknowledge the success that you've had and what you've gone through as a group, but I guess for us the bigger global picture and what's going to deem you're a success or not is tomorrow's match.
"It probably keeps us on even footing that both of us have been through that match last weekend."
The Heat won their semi-final on the final ball of the match but missed the end of the Sixers' win because they were flying back to Brisbane.
"We missed the last ball of their game because we were literally taking off," Short said. "So we'd stretched the airplane-mode capacity to its fullest so we'd taken off and gone home and had actually no idea until we landed in Brisbane what had happened and I think that was kind of a nice reset.
"For us, it was a bit of a shame the Renegades didn't win because that would have meant a home final for us. But I think at the same time that lovely recalibration of 'okay, that job's done, we've got home, we've got a week of training before we go again'.
"So I think for us it was the closure on the day in that we flew home that afternoon."
Short suggested that her bowling attack would take confidence in the knowledge that they restricted the Sixers to a small total the last time they met. It is a significant challenge: below Perry and Alyssa Healy, the Sixers boast an enviable pool of batting talent in Dane Van Niekerk, Ashleigh Gardner and Erin Burns.
"Lightning may or may not strike twice," Short said. "We'll take the 88 for sure. I think what that does give us is we know the plans executed were the right ones. The magic of cricket is trying to do that over and over and consistency is obviously that clichéd thing in sport but really is the key to performing in big moments. So we know that well-executed plans with considered planning get the job done."
Cricket Australia is hoping for a sellout with around 4,000 tickets sold just one day out from the match. Capacity for Drummoyne Oval has been set at 5,000, but ESPNcricinfo understands that there is some flexibility to extend that number if required.
Short hoped that there would be a significant number of neutral fans present to buy into a strong state rivalry and cheer for a new WBBL champion.
"It's interesting that tall poppy syndrome, isn't it?" Short said. "I mean, credit to the Sixers, they continue to show up in grand finals and they continue to win them and I spoke last week about the New South Wales cricket thing as much as the Sydney Sixers thing.
"It's probably a politically incorrect thing to say but I do know there is a little bit of a swell of support for us. It's that underdog Australian mentality, isn't it? It's like, well they've won enough, so maybe it's someone else's turn. Either way, we'll have a good crack and if there's a few extra different colours in the crowd cheering for us, then that would be nice, too."
