You're saying stopping cartridge.

And you're saying less power than a 500JRH.

I think you should reconsider the vernacular.

It's fun to play with new cartridges, and to wildcat cartridges.
It's also important to get perspective.

There's a group of fellows who have been having yearly gatherings in the company of big nasty bovine opponents, specifically for the purpose of testing handgun cartridges on animals who often display the interest in stomping them into grease smears in the dirt.
They call their group sessions the Bovine Bash.

It's been found that having simply enough energy to penetrate the animal's flesh is almost always not enough to get the job done of "stopping" the animal.

It appears to be necessary to not only smash through tough hide, big and sometimes interwoven bones, and tough flesh - and to reach and destroy the vital organs, but it's become apparent that it's also important to significantly hurt the feelings of the big nasty animals in order to turn them and to change their plans, and ultimately their direction.

44 magnum with seriously big powder charges over long and hard wide flat nose bullets can get adequate penetration. It takes *more* in order to hurt their feelings.

This is the common finding after hundreds of kills on huge nasty bovine opponents.

It's a lot easier to stop a big pig, or a large deer, or perhaps a determined black bear - but to call *any* handgun cartridge a Stopping Cartridge might be a bit of a reach.

Have fun with dreaming up a cool handgun project, but don't fool yourself while you are at it.

By the way, 500S&W can be a parent case for making 500JRH cases, and you can run 500 Special in the same lightweight revolver platform that the 500JRH is based on.
There's no practical or economical reason to limit yourself to the 500 Special when there are 500JRH reamers out there in the wild. It's the same gun, only the 500 Special limits you.