I have welded those tabs on before..and even fixed cracked bellhousings. All have been from botched installations. All have worked fine. If you broke it wheeling then more might be bent and a good idea to replace the case or cut the housing off for the ultra bell. For sure you won't break a bell housing again.
More common, it seems, is to break the back of the tranny off. I broke mine right through the pan (And didn't hurt the bell part)
I also have a turbo 400 with a SuperBell attached but don't like how they are attached to the pump housing. They were really developed for exploding converters with tranny strength a second feature (if at all). In the last couple years there have been some transmission gear explosions. Being that our butts are right there, many of the smart builders are using 1/4" T6 alum plate for flooring or adding a scatter shield.
Today, I would buy the Reid case and bell housing and be done with any worries at all. The soild case with bell is in the $1900 range. I would give Reid a call because the bell you could buy for your present 400 might fit their legara case in the future. Many talk about builds from $6-10k+ but relatively stock internals work for probably 90% of the offroading applications.
I'm on the same page with Dustin. The guys at Reid live offroad and could help guide you in the right direction knowing your wheeling and application.
Super Hydra 400® - Offroad version