As this is hopefully down to the last few hacks, I thought I'd ask if anybody wants to try this one:
Just to show that the crest in the background is a sprite, and not part of the tile data. The background, however, is part of the data (though the title initially shows blue against a black background, before it switches in the background palette).
I'm thinking a little title "Deep Dungeon II" and "The Hero's Crest" in big writing below?
What's left to do, I think, is to work on the proper ending, as well as fixing up the option to import a Deep Dungeon 1 save.
(I may need to do that separately. AFAIK, no emulator will allow me to swap games without auto-resetting.
So, I'd need to paste DD1 as a second disk to DD2 (a fake two-disk game) and hack that. Then merge the edited DD2 program file back into the main hack.
Hopefully, it's just tediously adjusting a few pointers.)