Please help before I start my new project

If I don’t use the filatura di crosa scozia cashmere yarn which says it’s bulky on their website but doesn’t give a number 1-6 should i use a 5 bulky yarn to replace it or do i use something else. based on another website it says to use 2 fine but i don’t think that’s right because it is going to be heavy item. i’m making a cape with a faux fur border. the gauge is 25 stitches and 28 rows to 8" in stockinette stitch. Please help I’m going nuts!

Look at other bulky yarns and match another yarn to the gauge - it’s a bit more 3 sts/inch - on the same size needles. Or plug in the FdC yarn into yarndex.com, get it’s gauge (may be a little different than the pattern) and look for those that are similar.