You are talking about an amount of power , but this amount is not known.
Only Kishimoto can answer , only himself know how strong was Hagoromo in his prime.
But , here are some signs that he didn't give all his power to NaruSasu.
-Hagoromo never lost his 2 ended sun/moon staff , staff that seem to have a relation with the will of fire/will of hatred.
-We don't know what Hagoromo could do with his Yin Yang mastery , I bet that what we saw of his power (levitating , rinnegan jutsus , nunoboko sword , Naruto's Yang releases , Sasuke's Yin releases...) was just an idea of what he was able to do.
In this case , Hagoromo would have given just a little Yang and Yin power up to Naruto and Sasuke , and he would have plenty left in his pockets.
In this case Naruto and Sasuke would be fodders compared to Hagoromo.