Needle size/yarn weight

This may be a silly question but…
I have a pattern for an afghan block but it is written for DK weight and I am using Malabrigo Merino which is a worsted. It says to use size 6 needles with DK weight yarn for a 12" square cast on 40 stitches (or multiple of 8+2) Not only does the math not work but I would like to use size 8 needles (or 7 but preferably 8) with the Malabrigo. The pattern is the “Lacy mock cable cloth” on Ravelry.
Thanks for your help.

Don’t use the worsted on the smaller needles, it may be very stiff and dense, go ahead with the larger ones. You’ll get bigger squares so you may need to make less of them, or have a larger blanket.

I came across this chart recently that may be of help to you.