... yes, max is a proprietary format and it is not likely an importer will ever come to existence ...
I have a rough plan of the Castle class; it includes plan views of the Squid (size 50 x 150 px for all 5 views -- not very helpful ...
).
I am not aware of any Hellcat in SH3 or SH4 but, note, I am no SH4 expert
