I still think it is India's attempt to copy it. They don't clone like the Chinese do, but like other nations pull the concepts.
India didn't attempt to copy the SA-6, it just found the general layout useful to implement a ramjet system and went ahead and developed a similar system. There is nothing in common between the two missiles in terms of materials and subsystems, though. Even the guidance is different, the Akash uses CG versus a SARH system on the SA-6. Where things get even more different is in the ground based system which after all, is the heart of any SAM system, where the Akash system is more akin to the layout of a high end SAM system like the S-300 with a PESA FCR . It also has a C3I system which automates the entire engagement system, end to end and also has a regiment/squadron level C3I getting inputs from a long range (150 km class) 3D radar. The entire system is highly mobile and comes in two different versions - one on trailers for the AF, the other on T-72 tanks for the Army.
Bottomline, this is clearly no SA-6 copy. Its a pretty unique system evolved to meet IA & IAF requirements framed for a missile in the 20-30km class, able to engage a wide variety of targets with high SSPK and also able to stand up to heavy opposition (strike packages with ARMs, EW etc). This is what led to this configuration.
The choice of ramjet was to give the missile an all the way thrust capability which was state of the art in the 1980's. Given only the Russians had a working ramjet SAM & which was also in Indian service, it was logical to evolve something that at least had the same overall layout, as it could be validated in windtunnel tests and would at least have similar baseline aerodynamic performance.
However, India's requirements meant everything went different after that. Akash uses CG as an ARH seeker was impractical, costly, and did not give adequate performance benefit. But the need for high ECCM capability led to the development of a PESA, with multi-target handling capability (2-3 missiles per target, upto 4 targets per radar) unlike the SA-6's which combined less capable systems on TELARs.
Similarly, the Indian requirement for the Akash to be deployed in areas where the ADGES could not support the system meant the development of an entirely new long range sensor, the 3D CAR. The automation meant that the system could be "fought" in almost all conditions without human intervention losing out to complex battle scenarios. The Akash system as far back as the late 90's began working on an all digital display system with extensive signal processing as versus even the S-300 exports at the time, which had the conventional phosphor screens.
The point is the Akash is uniquely configured to Indian service requirements of the IAF and Army, which were developed with an eye towards the future in mind. There is no other system out there with the same exact configuration for the Akash to be a copy.
Similarly, the cancelled Trishul project had a missile which looked externally like the SA-8 Gecko.
But thats where the similarities ended. The missile within was entirely different. It had a dual thrust propulsion system which was fairly radical at the time, and modern by todays standards. The Indo-Israeli LRSAM/Barak-8 project for instance uses a variant of the same technology today.
So don't go by looks but look at the doctrine, and whats within & the differences become apparent. The Akash C3I system, bar the radars was used by India to develop the Brahmos system. A lot of the technology went there. That sort of stuff is not apparent at first sight. But its what differentiates the Akash from the sort of one-to-one copies the Chinese turn out.
India has taken the harder path versus the Chinese, it tries to innovate across the board and is open about taking technological assistance where it needs to. This sort of disruptive development methodology means India's task is much harder and riskier - which mean delays and all sorts of developmental challenges. But over time, this is what will also ensure Indian developers keep innovating as versus copying as the Chinese have been doing in many systems. If China were to buy the Rafale, it would rip it off, and try to make one-to-one copies even with inferior systems. India would rather evaluate the Rafale, see what technologies it likes and work with France in a joint-IP sharing mechanism to develop something more evolved for its specific needs. I think this is a better approach than just copying. This is not to say China does not innovate. That it does, but there is a significant mindset issue of just aping what the other guy does, because then it must be good. They tend to do that a lot.