First of all, those numbers are kinda not accurate. Because they've stated that the current SCU will "scale" to the ship. Meaning that the "ranks" of the ships should be in the proper place. Relative to eachother.
That information is taken from:https://robertsspaceindustries.com/comm ... ISC-Hull-B
Which has the "newest" updated SCU list with decimals. But it's still 2 years old
And another example is that there's a difference in cargo for the Starfarer Gemini and the regular Starfarer. Yes, per now it's a copy of the interior, but I expect some changes in there(other than color), since it's now Aegis that has modified it, and it currently does not look like an Aegis ship. For your numbers it does make sense today, since they are equal in size on the interior, but the fuel and cargo modules in the back will probably have one standard, one size.
And to keep the "rank" of the ships SCU you must scale them down equally. Not have the Caterpillar be cut by 50% and then have Aurora CL be cut by about 66%, then they won't keep their "ranks" compared to eachother. I can agree that the new SCU might be on the 600i and so that doesn't get scaled etc.
And why did you scale 300i down from 4 to 1, and not the Avenger?
I guess you used the mass and the interior space to come up with this? But if you look inside 315p(which now has 2 Khajjah SCU) and the interior of the 300i(which is pretty identical) and then the Avenger, isn't that about the same size?