If you are just doing a label, I would think you could use what you have. I have a ton of embroidery thread because I do a lot of embroidery. I have also use some of the variegated threads to do some of my FSL (free style lace) (when I do wash away type crosses), that works okay.
If you do a lot of embroidery then you would want to invest in the various threads, if not use what you have. Do a sample first with some muslin to see how it works out for you.