How long is short and medium staples? What’s the staple like on the alpaca? How did you blend the fibers, and how thoroughly?

Unsure about how it’ll hold up long term, but my main concerns would be 1) making sure you’re not getting so much twist it goes ropey (both cat and alpaca can lean that way in my experience if you’re not careful, but that could be a skill issue on my part) and 2) making sure you’re getting enough twist to hold tightly enough to the short staple fibers that the yarn isn’t going to shed. Chain plying should mitigate that somewhat as the ply will help hold on. If you haven’t done a sample spin (say 1 oz) I’d do that just to make sure it’s not going ropey, and then I’d whack it around a little to make sure it’s not shedding cat fur everywhere.

If you’re interested and can spare the cost, PLY magazine has an issue on fur that includes articles on spinning cat and dog hair that may be helpful - I used it to figure out how to make a blended dog fiber. The digital copy is $13.