here's the CV roster for IJN
both lines start at the mogami & end at the "de grasse" at lvl 120

asuming you have the kaga now you can remodel it at 97, or buy the next one at 103 depends a bit on if you are high in credits (lvl 120 cv costs 50 milion credits + 20m points)
remodelling can be a credit sink if you are short, then i'd level past it to get the shinano

and you can start any nation cv from 0, just have to look into what you want to do with it before you pick a nation.