The OP asked about combo guns,, and in the Ruger line,, the Buckeye Sports convertible comes to mind. I don't think Ruger ever made any other models that were convertible. BUT,,, the 327's are very capable of handling the rimmed .32's from the little short all the way up.
And as for the number of the .32 H&R mags in the Single-Six size. Ruger had different models & it is a popular gun to enjoy. I recall way back when they were introduced,, thinking; "Nobody wants a .32 anymore,, these things are not gonna sell." Well, I decided to get a couple & put them away for later on, thinking they'd be a neat addition to my collection. Especially thinking they'd rise a lot in value. I found a NIB Bisley and got it. Then I found a used shooter with the plow handle.
I made the mistake of shooting the plow handled one. They are excellent guns, and caused me to realize I was wrong about them not becoming popular & selling well. Ruger has done quite well in making several .32 cal revolver models.
I also own a Blackhawk in 327 & a Buckeye convertible. Love them all.