If you don't like .38 than.357 probably won't do much for you either.
You seem to .4x calibers, so IMO a .44 magnum would be a good option.
Why not do a moon clip .45acp model?
I do suggest staying with calibers that are either commercially readily available OR can at least fire a commercially available caliber. (e.g. .454Casull can shoot .45LC)
Sic Semper Tyrannis