Hi
I'm by no means the expert here, but being Captain Obvious, the first problem is that the holster you're showing is built for a belt. Unless you build a new holster OR totally rebuild that one, it won't go over (into) the slot in a Busquedero belt. So right off the bat, you're building new holster. If I had to meet your requirements, I'd build a Busquedero belt and a new Mexican loop belt. Will Ghormley's new 3:10 to Yuma package deal has a way to put a snap so that the holster won't ride up when drawing quickly. I'd look at that idea.
Next kind of stupid idea, but based on experience. You could build a belt with a hanging belt to make it a Busquedero rig. I would connect using Chicago Screws somehow. I tried building what is effectively a Molle version of the Busquedero belt using the large Tandy Snaps.
A friend of mine has a light weight hunting backpack with Molle connectors on it. He has an ancient S&W semi auto from the 1990's and an old belt holster made for that pistol. I made 2 4 inch long belts to connect to the Molle gear, one with Snaps (the big Tandy ones). When wearing the one with Snaps to old the end on, he slid down the hill and lost the gun in the holster. He did find it in the morning.
Just my $0.02, and not worth much at all.