I doubt you will find a ready made front break holster for a Ruger SP101 with
4+ inch barrel. I suggest you look at Rusty Sherrick's web page.
C. Rusty Sherrick Custom Leather Works - Custom Concealment Holsters
He makes an (almost) exact copy of the Berns-Martin Universal Speed
Scabbard, on which Bianchi's 27 & 2800 were based.
Being a custom maker he can probably make what you are trying
to get.
As I recall, we have been down this road before, a year or so ago
You are left handed, even more reason to think custom maker.