I would use neither. Unless you have a lot of time on your hands to figure out the burn rate. You could wet it, grind it, and make some sort of a slurry with a binder to slow it down, and pack it in some sort of a small hollow shoe lace then dry it out.
With the smokeless you could try mixing it with acetone, it will turn to Goo. Then coat a fine string with it. The problem there is I don't think it will have enough oxygen to burn through your fuse hole unless you make a 1/4" fuse and your fuse hole was is 1/100 of an inch thick.
Is say if you can't get cruddy fireworks to steal fuse from, just get a bunch of books of matches, and some masking tape.
Cut all the match heads off and stick them along one edge of the tape so they are all touching. Once you have the length of fuse you need, start on the match head side and roll it up tight. It should be close to the size of your common cannon fuse, with a similar burn rate, and plenty of oxidiser to burn confined. Hell you could pry use a light coat of glue and water proof it if you wanted.
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