Your machine should work fine and 4 oz leather is also about right. Personally I would not used a milled shoulder from Tandy as it is too soft. This may be better https://www.tandyleather.com/en/product/craftsman-single-shoulders at $40 for a first leather project. There are many other finished leather choices as well. I have liked using 2/3 oz for linings and pockets. You could probably use the same thread and needle size you use in your for your nylon sewing. Make one see how it goes and adjust (needle change, thread change, pocket configuration...) You are stuck at home just get busy and enjoy it as much as you can with a broken ankle.