Van Gisbergen shocked the motor racing world earlier this month when he became the first driver in modern NASCAR history to win on debut.
The sensational victory came on the streets of Chicago with the Kiwi taking over the Project 91 entry at Trackhouse Racing.
It has now been confirmed that the Supercars regular will return to the Cup fold for the Indianapolis road course race next month.
That will be a different challenge for van Gisbergen given the Cup regulars having experience on the track, while Chicago was new for everybody.
Street circuits are also very familiar to van Gisbergen with four of them on the current Supercars schedule.
Still, Richard Childress Racing driver Busch remains convinced that van Gisbergen will be hard to beat at Indy, even if his advantage over the field won't be quite as big.
“I would say he is the favourite going in, for sure," he said.
"I would say that the gap will be closer from Chicago to the rest of the field that he had. He had us all beat by six-to-eight tenths of a second a lap.
"I would say going into Indy we should all be within two-to-three tenths, but he will still be the best guy.”
Van Gisbergen's return to NASCAR comes amid fevered speculation that he will make a full-time switch to US stock cars next season.
He is technically contracted to Triple Eight for the 2024 Supercars season, however is known to be unhappy with the new Gen3 cars.
T8 boss Jamie Whincup indicated after the Chicago win that he wouldn't stand in van Gisbergen's way if a full-time NASCAR ride became available next year.
Van Gisbergen won't be the only Supercars driver in the Indy field with Brodie Kostecki set to make his Cup Series debut in a third RCR entry.
Busch is expecting Kostecki to be an asset to the squad for the race, based on a joint test they undertook earlier this year in a Holden Commodore Supercar that's owned by RCR in the States.
Supercars have become a suitable test mule for NASCAR teams given the similarities with the current-gen Cup cars.
“We tested together our V8 Supercar that we have at RCR earlier this year," Busch explained. "He was there when we first went out and I think he had me covered by about two seconds a lap and then as the day kind of progressed, by the end of the day, we actually ran times that were real comparable and right on top of his.
"It just took me a while to get used to those cars and what they are and how you can really attack corners. Just various driving techniques that those cars take.
"But I think those guys are all very good at what they do, and they really understand the heavy stock car feel and basis for these road courses. So, I would assume that [Kostecki] will be strong as well.
"Hopefully I can lean on him and learn a lot from him and have some time in the sim and stuff like that with him that will allow us to be better off when we get there."
