Blast-Attak was one of my favorite characters as a kid. I always liked his Frankenstein/cyborg appearance. I also liked that he was part of the Snakemen, as was stated in the mini-comics.
Some people have said that they think a MOTUC version would require a whole new body mold to produce a figure, but I think that much of the figure could be made of existing parts. (Of course, some of these parts don't exist yet, but I am sure they will in the near future.)
I think that "NA" Skeletor's arms and gloves attached to Trap Jaw's shoulders would work well. They could also use the legs from a New Adventures figure for Blast-Attak, such as Optikk. As for his chest armor, it could be a removable armor placed on a Hordak torso.