Australia Sovereign 1866 Restrike ?

You are showing pictures of two different coins.
Which one are you referring to?
Also a restrike is not a genuine coin, it is a replica.
PCG is what is known as a basement slabber and unreliable.

With the pictures I see on my 24 inch screen monitor, this coin appears to be authentic. I agree that it appears to be well struck.

Just to note that Type 2 (1857-68) 1866 Sydney Mint sovereigns are yellow gold (2 carats, 8.33% silver), not red gold, (2 carats copper). Some of the Type 2 Sovereign issue of 1870 was in red gold.
Hand held XRF instrument should confirm.
Take it to a bullion dealer to confirm, they will most probably charge a fee for this service. They would almost certainly give you accurate weight information at the same time. (7.9881 grams)

I have never heard of an Indian grading company who call themselves 'PCG'. Indian 'PCG' would have very little recognition in the American numismatic collector market. Although Indian mints are notorious for the production of restrike coins (mainly Indian), I have never heard of restrike Sydney Mint sovereigns before. In my opinion, Indian PCG is incorrect.
If the coin is in a slab, and your decision is to test it for weight and alloy analysis, is is necessary to break the coin out of the slab.

I only use Sheldon for American coins, when I can visually compare with PCGS Photograde
Good EF (British grading)
I currently have an example of an 1866 Sydney Mint Sovereign in my collection
My example by comparison, would grade at
good VF.

Looks okay to me too. It also looks like there is a die clash on the reverse.

with Mr T

Die clash on the reverse