Hi Miguel!
I don't know if the superstructure will fit the ISW kit. If someone with the ISW kit in hand can give us the 01 level dimensions, we can compare those dimensions to the dimensions of the 3D superstructure. If the ISW kit is a little bit smaller than scale, the 3D superstructure may fit the ISW kit well.
When I began the design for the BWN/YMW kit, Martin Quinn graciously sent me a BWN/YMW kit to make sure the 3D design would fit. As you know, because of the nature of the resin in resin kits, many factors affect them as the resin cures which can affect their final dimensions, especially noticeable in larger kits. (Designing products for them is high adventure!)
When I compared Martin's BMW/YMW kit to Booklet of General Plans drawings, the kit's 01 level came out a tad bit shorter and narrower than scale, a very common characteristic of large resin kits, probably due to shrinkage when curing. The barbette is smaller than scale, too.* So the superstructure I designed accounts for those two differences.
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*This can be a problem if you use 1/350 true-scale Model Monkey Colorado class turrets on the Model Monkey 3D superstructure. The true-scale Model Monkey turrets are precisely 1/350 scale so when you put a MM turret on the smaller-than-scale BWN/YMW-sized barbette, turret #2 will rub up against the conning tower.
A separate set of turrets and barrels specifically scaled to fit the BWN/YMW kits and Model Monkey superstructure is now available. Link: http://shpws.me/PknV