Probably too late to help OP, but iirc on the curado 100b's you have a lifeline for spool availability as the Curado 100D (and 100DSV), Citica 100D, and Chronarch 50 Mg spools will fit in that reel (and spools are not handed so same applies to lefties). I know the reverse is true as I've used a 101B spool in a chronarch 51 MG to get a little more casting distance from larger stuff.
The curado 100DSV spool is available straight from shimano, for example, for 22.13 plus shipping/tax.
https://fishshop.shimano.com/vip/landing.jsp#(I couldn't get a direct link to work, but just go to the parts tab, then click on Curado and enter the model #).