G70 is not high enough to get away without galvanizing, and it is possible to obtain hot-dipped high tensile. It's often branded as "transport" chain in the US, don't know where you are. The galvanizing reduces the tensile strength a little, which is factored into the WLL figures.
As SD implies, you will also require calibrated chain if it's to be used on a windlass gypsy, it doesn't sound like the finishes you mention are likely to be.
High tensile is a good idea as it allows a considerable amount of weight to be saved from the bow of the boat.
There is more info on grades and sizing for anchor chain here, it's an attempt at a fairly complete guide to selecting chain for anchor rode: Chain (Rocna Knowledge Base)
One thing about the High-test grades of chain, like G43 and G70, you have to examine the links for distortion if the chain is ever exposed to very high stresses...the links can deform and fail rather suddenly when loaded a second time. While this is true of all chain, it is particularly applicable to high-test chain.
I ran into the problem of buying lighter weight high tensile anchor chain only to "discover" that the reduced size, and weight, of the chain would only allow shackles to fit that were much weaker than the high tensile chain's rating.