You're likely to find that's pretty "snorty" for eating meat on small game. I haven't shot Swiss, but my understanding is that it's a little "hotter" than comparable granulations of Goex.
I based my 30-35 grain charge on the volume of the patent breech in the Lyman, as measured and reported by someone here on the site. I would love to go lower than that, but worry about having an air space under the ball, since it's going to stop at the junction of the breech and barrel.
I'd be using 2f Goex for a little slower burn and even lower velocity, but in my guns it's pretty fouly in small charges. If Swiss is indeed a little hotter and clean burning as everyone says in the first place, it likely will not be so fouly.
One thing for sure: I used to use 60 grains as my universal plinking and small game load until I dropped a ball into the neck of a snowshoe hare. Pretty well lifted the head right off and left both shoulders and the front of the loin so bloodshot I couldn't save them. Reminded me of the same shot with a fast 25-20 Win I own (1800 fps).
I'd sure try 30-35 grains as a start, then work up the scale in increments only if you weren't happy with the accuracy or fouling. Then I'd be REAL careful with shot placement.
In any case, I'm betting you'll be delighted with that little Deerstalker in the field. It's a joy to carry, and if yours is like my wife's, accurate as a snake bite with almost any charge.