Hey Bazooka-Face.
I know, it's been a hot minute again, since you last posted on here, or when there was any action in this thread, in general. I hope you are doing fine!
I was playing 'Doom+Doom II' on Steam, the other day, browsing through some of the mods there (they have such a horrible system on there, to look through, what mods there are), and I noticed several 'Doom64 to Doom (2)' kinda mods.
I was asking myself (and now you) if this is something, that could be possible, for the GBA. I have to admit, that I am too much of a dummy, to really understand anything, in terms of what is possible and what isn't. But as far as I get it, those so called 'Total Conversion Mods' are out of the question – which is understandable, because the GBA couldn't handle those anyhow... and I think it has to be 'compatible' with PR Boom or something.
Anyway, I don't really understand it, but as I scrolled though some of these mods, I wrote 3 of them down, which maybe could be possible. One of them even mentioned, having the maps of Doom64, while staying vanilla compatible.
1.)
The first one and the one which mentioned, that it would stay vanilla compatible is called 'Doom 64 for Doom II' on there. I myself only scrolled through the first 18 pages of those mods. So it has to be among those somewhere.
2.)
Another one was called 'Doom64 for Doom2 + Doom64 Sprites&Sound'. I guess, since this one already sounds like not very vanilla-like, that it would be a No-Go for the GBA.
3.)
A third one, I found, was called 'Doom64 Sprites for Doom II'. As the name implies, these aren't the levels, but only the sprites, as it seems. I don't know, if this would work at all, but maybe it would be possible to replace the weapon models of the GBA Doom, with the ones from Doom64.
Anyway... I hope any of this info was useful and I wish you the best!