The Cattlemn are B/P. Uberti made a run of SAA's which have B/P cylinders which are loaded off the gun, using a small press. Caps are fitted to the nipples via the loading gate. Armi San Marco also did a version, but it wasn't as nicely finished.
As for a "bigger" .36, have you looked at Pietta? They chambered some of the 1858 Remy copies in .36 and called them the New Model Navy, or something like that.... Uberti also do a .36 Remington.