If I had to guess, I'd say the scale is 1/200, because most of the display models I've seen in Gakken books and pictures of the displays at the Kure Museum are in that scale and it is my understanding that you are associated with the modelers who have built most of them. There is also the possibility that you are working in 1/100 scale that some modelers have chosen for very special projects. Since you've been working on it for 25 years, that may qualify as one of those.
Back in eary 70´íes a pioneer modeller &researcher/maker of model parts proposed all IJN ships models be built in 1/200. and that they should go to a museum.
He had lots of club members/modellers in his assosiation;they danced with him, but only in the beginning.
(many modellers are too indivisual, egos only, thinking only of favorite ships they want to build,
they aren´t good as collective modellers for the purpose of a joint-project)
As I recollected,his dreams got larger,began building in 1/100, grew into 1/50,then he settled down on 1/10.
After the death his dream was materialized,now his works at Kure Yamato Museum. Was a father-like existence for me.
I doubt that you are working in 1/50 scale because you haven't mentioned any provisions for getting inside and sailing it. 1/50 is absolutely not a cup of my tea,I know some gets a kick out of such an indulgence as you wrote;
mine is
strictly on still models, nothing but still models. :
Deviations and diversions unthinkable for me.
But I can be one of them who believe models ought to be in 1/100 at least,without use of plastics,regin material
and the like as prerequisites for museum pieces,,
I've seen pictures of 1/700 and even 1/1200 (the Skulski Takao) that look like they could have been 1/350 or even 1/200 because of their level of detail. Just as you have demonstrated with your research, I didn't think a guess was adequate, so that's why I asked. Thank you again for sharing,Mike Regarding this I´ll be posting my comment later, when i have time.
thank you.
Mutsuo S.