3126b and the c7 are different. very similar, but definatly different.
as for re-rating goes, if you say yours is at 190, the highest cat will let you go is 210hp/605tq.
the c7 is available in ratings from 190-350, but to get 230+ for your engine they require different pistons, turbo, injectors, and a viscous damper.
i would definatly go for the 210. its only 40 hp, but its 80ft/lbs more, and im assuming that at 190 the truck is a slug.