pt 1 Kakashi would give him a good fight, he even has chances of winning.
Enma was immobilized by a few snakes, i see Kakashis nin-ken are doing the same coming out of the ground surprising enma.
With the 3T Sharingan Kakashi is able to keep up with hiruzen in taijutsu, he even can open the 1 gate to use 100% of his muscles (thats 5 times more than humans normally does) to surpass old hiruzens taijutsu. His speed is defentley better than hiruzens even without the 1 gate.
Hiruzens fire is counterd with water, doton and raiton is overcome with raikiri, hiruzens suiton and fuuton gets tanked/avoided with earth wall or doton hiding like a mole.
A kage bunhsins kills the immobilized enma, while the original fights hiruzen.
Kakashi would be drained hard after the fight, but he can win this high diff 4/10 times
war arc Kakashi laughs at old hiruzen and enma, he didnt need his nin- ken, his kage bunhsins fought v2 jins and the manzo. One beast runner paralyzes enma followed by raikiri kunai to the head.
He is even more faster and improved in every other area a lot. Hiruzens attacks are dodged easily, he would hold himself a few minutes against kakashi but in the end Kakashi med diffs him.