I'm not sure if this thread is still alive or not, but one way to spin it would be to lean into a similar sort of tension used in the Innistrad campaign setting: necromagic vs sanctifiedmagic. (To a lesser extent, this is also what drove the drama in the Darksun campaign setting.)
Basically, reflavor "guns" as "wands powered by the souls of the dead" and trains as "caravans hauled by the souls of the dead", etc. You can full necro-punk if you want to (a la Blades in the Dark), or keep it more gothic, like Innistrad does.
If you want to dip your toes in the water of "what high fantasy with guns looks like", I'd recommend Warhammer Fantasy. If nothing else, mine it for images to help set the tone. It's about 14th century level technology (think Thirty-Years-War in the Holy Roman Empire over the nascent Protestant schisms). It's *not at all* steampunk. But it does have Dwarves, Orcs, etc. and some of them are in musket brigades. Get your players to buy into "late medieval fantasy" and keep the "*-punk" out of it. FWIW, Warhammer Fantasy is grim-n-gritty, which is pretty antithetical to "steampunk" on a tone-level. Again, look at and share those pictures/art to help set inspiration and tone for Zeitgeist.
