I have several Morgan soprano pieces; Vintage, large-chamber Vintage, hard-rubber, all in #7 tips (.070) and one Vintage in #6 (.065). They are really good players for me on modern and vintage sopranos. Among the Vintage pieces, the large-chamber isn't quite as good as the regular-chamber, but that could be just MY embouchure.
I've recently downsized tip-openings, though. When playing the Morgans, I always adjusted my usual soft reeds (like Vandoren ZZ and Javas and blue-box #2's) to be even softer. Now with the closed-tip pieces I'm using (like a Selmer Concept at .042, Selmer S-80 D, and a scroll-shank C*), I use the same reeds but don't adjust them down a lot like I did with the open pieces.
I THINK the Morgans follow a predictable path down the measuring scale, in .05" increments but maybe "junkdude" (Dave Hoskins?, who sells Morgans) can tell you more about them. DAVE