Unfortunately 2013 Froome gets crushed by Pogacar. Then his biggest rival was a young Quintana, who put him in difficulty on the last mountain. But can we really imagine that a young Quintana troubles Tadej?
Nah, you are underestimating peak Froomey, who had great performances in that race (both mountains and TTs). Let's have fun and try to analyse their potential duel.
Ax-3-Domaines: Froomey was flying out there gapping the rest easily and was supported by super-strong Porte. Pog could have climbed that mountain very fast too, maybe even faster than Chris. I think this would be close: whoever is the weaker one would be able to hold the wheel of the stronger one. Pog gains bonus seconds at the end.
Ventoux: Froomey was very strong there dropping Quintana, who already was a great climber. Pog actually showed some weakness on the biggest climbs of his Tours so Froomey puts 30 seconds into Pog.
Mont-Saint-Michel TT: another superb performance by Froome. He puts some time on Pog again but not much (under 30 seconds I guess).
Chorges mountainous TT: Froome strong again edging Contador there but Pog is strong on this course too and puts some time into him here (but is still behind in the GC).
Semnoz: Pog has to drop a watt bomb at some point, right? And this is a perfect climb for him. He smokes the mountain achieving 1800 of VAM for half an hour, puts over a minute into ailing Froome and wins the race at the end (but by less than a minute).