Could you potentially turn them into two separate scenes? One scene could be where Kylo is on his Star Destroyer, and he touches Vader’s helmet to confirm Palpatine’s claims and gain insight on how he survived, a look into the past.
Then Rey’s training montage would be separate, and Rey could have her own brief vision, maybe a brief glimpse into the future.
Maybe that could be another way to help slow the film down. Either way, I think there might be some flexibility as far as how this scene could be edited.