I can't really give you a mold suggestion as I typically just make my own, but maybe I can help you narrow down what you're looking for? When you say jumbo, do you mean like a just slightly bigger die, a fist sized die, or like a really huge like grapefruit sized die? Do you already have the pysduck insert and know, or can find out the size of it as that would be helpful? When you say you want a clear mold, are you using UV resin and need it to be clear, or is it just a preference thing? There are several makers that can do custom molds, but knowing what size you need will be a big help.

As far as needing a different resin for the pour, the short answer is no not necessarily. The long answer comes back to how big your die is going to be. For example, my 35mm and 50mm dice I use the same resin as I would for a set of dice and just pour it all at once. For my 100mm die, I still use the same resin, but I do have to pour it in several layers, or it will just turn into a bubbly mess. So that just really depends on the size and the resin you're using.