Him winning against the 3rd raikage means nothing when it comes to him fighting A.
They're two totally diffrernt People.
Naruto's strength is increased, but i would bet A has more Brute strength, Even in Km mode naruto said if he takes a direct punch from A he is finnished. Sm mode would provide a little protection but if he takes a direct hit he will take some serious damage.
Problem is naruto wouldn't be able to hit A, Rs wouldn't touch him, i doubt Sm/Base clones will be fast enough either, even if he spams them.
Lightning armor would most likely defend any form of Tai Naruto has (frog kata)
A with his Taijutsu enhanced with raiton would cause naruto serious trouble, Naruto lacks the long range jutsu's needed, His best long range attack is Rs, It's not that fast and A can easily dodge.
Sure the Third and Fourth Raikage are two different people but that doesn't take away the fact they are extremely similar, both have the same fighting style, same chakra nature (and utilize it in the same way) and we know for a fact that the Third was stronger. Has it even been confirmed who is faster between the two because I don't think this has been officially confirmed.
Despite whoever was faster all I know is that they are both incredibly fast, I know that Naruto is able to at least dodge V1 attacks in Sage mode. I also know that Naruto killed the preta path Pain without even touching him with just one air punch. That tells me that a direct, physical punch from Naruto's fist would do twice as much damage. If Naruto takes a hit from A I'm sure it will hurt but Naruto will survive and vice versa. I just feel some people are underestimating the power of Sage mode and I believe Naruto would defeat A if he's in V1 mode at least.
V2 is where Sage Naruto has to watch out for, in this scenario I don't know how Naruto would avoid his attacks and speed, obviously he will be able to sense A coming at him, but the question is will Naruto be fast enough to react. The answer to that is arguably no, but that isn't for certain; plus Naruto is very smart in battle now, all he needs is one clean hit with Rasenshuriken to turn the tide of the battle his way.
Lets be honest, if these 2 actually fought Sage Naruto would obviously win due to plot no jutsu. That I know for sure.