well 3d weapons would be the only change to make and you could use the 3d weapons other people have made, sure they wont look the same as the ones in the game but what youre asking for is for someone that ports games source code to an engine running on the quest to start designing 3d assets to inject into the game. beauty of the gzdoom port is you can easily play any wads that run on the platform, if your that interested check out doom world and learn how to edit wads and have a gander at a voxel editor to change the guns to what you want, beefs already done the hardest part.