Yup, I totally agree. An 8" version of the AGS would be totally awesome. I think all-around, the 8" was the most versatile heavy gun of the modern era against both ships and shore targets
As far as I know, no one is making 8" naval artillery rounds anymore, so you'd have to develop both the gun and the ammo for it.
Well, USSR in 1970-th was thinking about navalized version of 2S7 "Pion" 203-mm gun...
So, you always could buy the russian shells.